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Update Turkish FAQ, Devrim GUNDUZ
2003-07-31 04:41:56 +00:00
PostgreSQL i<>in S<>k<EFBFBD>a Sorulan Sorular (SSS)
Son g<>ncelleme : 26 Temmuz 2003 Cumartesi - 18:32:11
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us
<mailto:pgman@candle.pha.pa.us>)
<EFBFBD>evirenler : Devrim G<>nd<6E>z (devrim@gunduz.org <mailto:devrim@gunduz.org>)
Nicholas Morris Tufar (ntufar@yahoo.com <mailto:ntufar@yahoo.com>)
Volkan Yaz<61>c<EFBFBD> (volkany@celiknet.com <mailto:volkany@celiknet.com>)
Bu belgenin en g<>ncel hali,
http://www.PostgreSQL.org/docs/faqs/FAQ_turkish.html
<http://www.postgresql.org/docs/faqs/FAQ_turkish.html> ve
http://www.gunduz.org/seminer/pg/FAQ_turkish adreslerinde g<>r<EFBFBD>lebilir.
Platforma <20>zel sorular<61>n<EFBFBD>z, http://www.PostgreSQL.org/docs/index.html
<http://www.postgresql.org/docs/index.html> adresinde yan<61>tlan<61>r.
------------------------------------------------------------------------
Genel Sorular
1.1 <#1.1>) PostgreSQL nedir? Nas<61>l okunur?
1.2 <#1.2>) PostgreSQL' in haklar<61> nedir?
1.3 <#1.3>) PostgreSQL, hangi Unix platformlar<61>nda <20>al<61>s<EFBFBD>r?
1.4 <#1.4>) Hangi Unix olmayan uyarlamalar<61> bulunmaktad<61>r?
1.5 <#1.5>) PostgreSQL'i nereden indirebilirim?
1.6 <#1.6>) Deste<74>i nereden alabilirim?
1.7 <#1.7>) En son s<>r<EFBFBD>m<EFBFBD> nedir?
1.8 <#1.8>) Hangi belgelere ula<6C>abilirim?
1.9 <#1.9>) Bilinen hatalar ya da eksik <20>zelliklere nereden ulasabilirim?
1.10 <#1.10>) Nas<61>l SQL <20><>renebilirim?
1.11 <#1.11>) PostgreSQL 2000 y<>l<EFBFBD>na uyumlu mudur?
1.12 <#1.12>) Geli<6C>tirme tak<61>m<EFBFBD>na nas<61>l kat<61>labilirim??
1.13 <#1.13>) Bir hata raporunu nas<61>l g<>nderebilirim?
1.14 <#1.14>) PostgreSQL, di<64>er VTYS(DBMS) lerle nas<61>l kar<61><72>la<6C>t<EFBFBD>r<EFBFBD>labilir?
1.15 <#1.15>) PostgreSQL'e maddi a<><61>dan nas<61>l destek olabilirim?
Kullan<61>c<EFBFBD>/istemci Sorular<61>
2.1 <#2.1>) PostgreSQL i<>in ODBC s<>r<EFBFBD>c<EFBFBD>leri var m<> ?
2.2 <#2.2>) PostgreSQL'i web sayfalar<61>nda kullanabilmek i<>in hangi
ara<EFBFBD>lar bulunmaktad<61>r ?
2.3 <#2.3>) PostgreSQL'in grafik kullan<61>c<EFBFBD> arabirimi var m<>d<EFBFBD>r?
2.4 <#2.4>) PostgreSQL ile ileti<74>imi kurabilmek i<>in hangi dilleri
kullanabilirim?
Y<>netimsel Sorular
3.1 <#3.1>) PostgreSQL'i //usr/local/pgsql/ dizininden ba<62>ka dizinlere
nas<EFBFBD>l kurabilirim??
3.2 <#3.2>) /Postmaster/'<27> ba<62>latt<74><74><EFBFBD>mda /Bad System Call/ ya da core
dumped mesaj<61> al<61>yorum. Neden?
3.3 <#3.3>) /Postmaster/'<27> ba<62>latt<74><74><EFBFBD>mda, /IpcMemoryCreate/ hatas<61>
al<EFBFBD>yorum. Neden?
3.4 <#3.4>) /Postmaster/, ba<62>latt<74><74><EFBFBD>mda, /IpcSemaphoreCreate hatas<61>/
al<EFBFBD>yorum. Neden?
3.5 <#3.5>) Di<44>er bilgisayarlar<61>n benim PostgreSQL veritaban<61> sunucuma
ba<EFBFBD>lant<EFBFBD>lar<EFBFBD>n<EFBFBD> nas<61>l kontrol edebilirim?
3.6 <#3.6>) Veritaban<61> motorunu daha iyi ba<62>ar<61>m icin nas<61>l ayarlayabilirim?
3.7 <#3.7>) Hangi hata ay<61>klama <20>zellikleri bulunmaktad<61>r?
3.8 <#3.8>) Ba<42>lanmaya <20>al<61><6C><EFBFBD>rken, neden "/Sorry, too many clients/"
hatas<EFBFBD>n<EFBFBD> al<61>yorum?
3.9 <#3.9>) /pgsql_tmp/dizinin i<>indeki dosyalar nelerdir?
3.10 <#3.10>) PostgreSQL s<>r<EFBFBD>mlerini y<>kselmek i<>in neden bir
dump/reload i<>lemi ger<65>ekle<6C>tirmek zorunday<61>m?
<20><>letimsel Sorular
4.1 <#4.1>) Binary cursor ve normal cursor aras<61>ndaki fark ned<65>r?
4.2 <#4.2>)Sorgunun sadece ilk birka<6B> sat<61>r<EFBFBD>n<EFBFBD> nas<61>l SELECT edebilirim?
4.3 <#4.3>) /psql/'in i<>inde g<>rd<72>g<EFBFBD>m tablolarin ya da di<64>er <20>eylerin
listesini nas<61>l alabilirim?
4.4 <#4.4>)Bir tablodan bir kolonu nas<61>l kald<6C>rabilirim?
4.5 <#4.5>)Bir sat<61>r, tablo ve veritaban<61> icin en fazla b<>y<EFBFBD>kl<6B>k nedir?
4.6 <#4.6>) Tipik bir metin dosyas<61>ndaki veriyi saklamak i<>in ne kadar
disk alan<61> gereklidir?
4.7 <#4.7>) Veritaban<61>nda hangi tablo ya da indexlerin tan<61>mland<6E>g<EFBFBD>n<EFBFBD>
nasil g<>rebilirim?
4.8 <#4.8>) Sorgular<61>m cok yavas, ya da indexlerimi kullanmiyorlar. Neden?
4.9 <#4.9>) Query-optimizer in sorgular<61>m<EFBFBD> nas<61>l de<64>erlendirdigini,
i<EFBFBD>leme soktu<74>unu nas<61>l g<>rebilirim?
4.10 <#4.10>) R-tree index nedir?
4.11 <#4.11>) Genetic Query Optimizer nedir?
4.12 <#4.12>) D<>zenli ifade (Regular Expression) aramalar<61>n<EFBFBD> ve
b<EFBFBD>y<EFBFBD>k/k<><6B><EFBFBD>k harfe duyars<72>z aramalar<61> nasil yapabilirim? Bu b<>y<EFBFBD>k(k<><6B><EFBFBD>k
harfe duyarl<72> aramalar i<>in indeksi nasil kullanabilirim?
4.13 <#4.13>) Bir sorguda, bir alan<61>n NULL oldu<64>unu nas<61>l ortaya
<EFBFBD><EFBFBD>karabilirim?
4.14 <#4.14>) <20>esitli karakter tipleri aras<61>ndaki farklar nelerdir?
4.15.1 <#4.15.1>) Nas<61>l serial/otomatik artan(auto-incrementing) bir
alan yaratabilirim?
4.15.2 <#4.15.2>) Serial giri<72>inin de<64>erini nas<61>l alabilirim?
4.15.3 <#4.15.3>) /currval()/ ve /nextval()/ di<64>er kullan<61>c<EFBFBD>lara sorun
yaratmaz m<>?>
4.15.4 <#4.15.4>) Neden sequence say<61>lar<61>n transaction i<>leminin
iptalinden sonra yeniden kullan<61>l<EFBFBD>yor? Neden sequence/SERIAL kolonumdaki
say<EFBFBD>larda atlamalar oluyor?
4.16 <#4.16>) OID nedir? TID nedir?
4.17 <#4.17>) PostgreSQL' de kullan<61>lan baz<61> terimlerin anlamlar<61> nelerdi?
4.18 <#4.18>) Neden /"ERROR: Memory exhausted in AllocSetAlloc()"/
hatas<EFBFBD>n<EFBFBD> al<61>yorum?
4.19 <#4.19>) Hangi PostgreSQL s<>r<EFBFBD>m<EFBFBD>n<EFBFBD> <20>al<61>st<73>rd<72><64><EFBFBD>m<EFBFBD> nas<61>l g<>rebilirim??
4.20 <#4.20>) Neden large-object i<>lemlerim, /"invalid large obj
descriptor"/ hatas<61>n<EFBFBD> veriyor?
4.21 <#4.21>) <20>u andaki zaman<61> <20>ntan<61>ml<6D> de<64>er olarak kabul eden kolonu
nas<EFBFBD>l yarat<61>r<EFBFBD>m?
4.22 <#4.22>) Neden |IN| kullanan subquerylerim <20>ok yava<76>?
4.23 <#4.23>) Outer join i<>lemini nas<61>l yapabilirim?
4.24 <#4.24>) Ayn<79> anda birden fazla veritaban<61>nda nas<61>l i<>lem yapabilirim?
4.25 <#4.25>) Bir fonksiyondan nas<61>l <20>oklu sat<61>r ya da kolon
d<EFBFBD>nd<EFBFBD>rebilirim??
4.26 <#4.26>) Neden Pl/PgSQL fonksiyonlar<61> i<>inden g<>venli bir <20>ekilde
tablo yaratma/kald<6C>rma i<>lemlerini yapam<61>yoruz?
4.27 <#4.27>) Hangi replikasyon se<73>enekleri bulunmaktad<61>r?
4.28"D <#4.28>) Hangi <20>ifreleme se<73>enekleri bulunmaktad<61>r?
PostgreSQL <20>zelliklerini Geni<6E>letmek
5.1 <#5.1>) Kullan<61>c<EFBFBD>-tan<61>ml<6D> bir fonksiyon yazd<7A>m. /psql/'de
<EFBFBD>al<EFBFBD><EFBFBD>t<EFBFBD>rd<EFBFBD><EFBFBD><EFBFBD>m zaman neden core dump ediyor?
5.2 <#5.2>) PostgreSQL'e nas<61>l yeni veri tipleri/fonksiyonlar ekleyebilirim?
5.3 <#5.3>) Bir tuple d<>nd<6E>rmek i<>in bir C fonksiyonunu nas<61>l yazar<61>m?
5.4 <#5.4>) Bir kaynak dosyas<61>nda de<64>isiklik yapt<70>m. Yeniden derlememe
ra<EFBFBD>men de<64>i<EFBFBD>iklik ge<67>erli olmuyor. Neden??
------------------------------------------------------------------------
Genel Sorular
1.1) PostgreSQL nedir? Nas<61>l okunur?
PostgreSQL, /Post-Gres-Q-L/. olarak okunur
PostgreSQL, yeni-nesil VTYS ara<72>t<EFBFBD>rma prototipi olan POSTGRES veritaban<61>
y<EFBFBD>netim sisteminin geli<6C>tirilmesidir. POSTGRES' in zengin veri tiplerini
ve g<><67>l<EFBFBD> veri modelini tutarken, SQL'in geli<6C>tirilmis alt k<>mesi olan
PostQuel dilini kullan<61>r. PostgreSQL <20>cretsizdir ve kaynak kodu a<><61>k
da<EFBFBD><EFBFBD>t<EFBFBD>l<EFBFBD>r.
PostgreSQL, PostgreSQL geli<6C>tirme listesine <20>ye olan bir Internet
geli<EFBFBD>tirici tak<61>m<EFBFBD> taraf<61>ndan geli<6C>tirilir. <20>u andaki koordinat<61>r, Marc
G. Fournier (scrappy@PostgreSQL.org <mailto:scrappy@PostgreSQL.org>).
(Bu tak<61>ma nas<61>l kat<61>lacag<61>n<EFBFBD>z<EFBFBD> <20><>renmek i<>in 1.6 <#1.6> numaral<61>
maddeyi okuyunuz.) Bu tak<61>m, t<>m PostgreSQL geli<6C>iminden sorumludur.
PostgreSQL 1.01 s<>r<EFBFBD>m<EFBFBD>n<EFBFBD>n yazarlar<61> Andrew Yu ve Jolly Chen idi.
Bunlar<EFBFBD>n d<><64><EFBFBD>nda bir ka<6B> kisi de uyarlama, hata ay<61>klama ve kodun
geli<EFBFBD>tirilmesi i<>in <20>al<61>sm<73><6D>t<EFBFBD>. PostgreSQL'in t<>redigi orijinal Postgres
kodu, lisans, lisans<6E>st<73> ve akademisyenler taraf<61>ndan, Professor Michael
Stonebraker ) University of California, Berkeley) koordinat<61>rl<72>g<EFBFBD>nde
yaz<EFBFBD>lm<EFBFBD>st<EFBFBD>r.
Berkley'deki yaz<61>l<EFBFBD>m<EFBFBD>n ad<61> Postgres idi. SQL uyumlulu<6C>u 1995'te
eklenince, ad<61> Postgres 95 oldu. 1996 y<>l<EFBFBD>n<EFBFBD>n sonlar<61>nda ad<61> PostgreSQL
olarak de<64>i<EFBFBD>tirildi.
1.2) PostgreSQL'in haklar<61> nedir?
PostgreSQL Data Base Management System
Portions copyright (c) 1996-2002, PostgreSQL Global Development Group
Portions Copyright (c) 1994-6 Regents of the University of California
Permission to use, copy, modify, and distribute this software and its
documentation for any purpose, without fee, and without a written
agreement is hereby granted, provided that the above copyright notice
and this paragraph and the following two paragraphs appear in all copies.
IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF
THE POSSIBILITY OF SUCH DAMAGE.
THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATIONS
TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
<EFBFBD>stteki metin klasik a<><61>k-kod lisans<6E> olan BSD lisans<6E>d<EFBFBD>r. Kaynak kodun
nas<EFBFBD>l kullan<61>labilece<63>ine dair s<>n<EFBFBD>rlamalar<61> yoktur. Bu lisans<6E>
seviyoruz. De<44>i<EFBFBD>tirme niyetimiz bulunmamaktad<61>r.
1.3) PostgreSQL, hangi Unix platforlar<61>nda <20>al<61>s<EFBFBD>r?
Genel olarak, modern bir Unix-uyumlu platform PostgreSQL'i
<EFBFBD>al<EFBFBD><EFBFBD>t<EFBFBD>racakt<EFBFBD>r. Ayr<79>nt<6E>l<EFBFBD> bilgi i<>in kurulum belgelerine bakabilirsiniz.
1.4) Hangi Unix olmayan uyarlamalar<61> bulunmaktad<61>r?
*<2A>stemci*
libpq C k<>t<EFBFBD>phanesini, psql ve diger arabirimleri ve binary dosyalar<61>,
MS Windows ortamlar<61>nda <20>al<61>smas<61> i<>in derlemeniz m<>mk<6D>nd<6E>r. Bu <20>rnekte
istemcide MS Windows <20>al<61>s<EFBFBD>yor ve desteklenen Unix platformlar<61>ndan
birinde <20>al<61>san PostgreSQL sunucuna TCP/IP ile baglanmaktad<61>r. Da<44><61>t<EFBFBD>m
i<EFBFBD>indeki win31.mak dosyas<61> ile, Win32 libpg k<>t<EFBFBD>phanesi ve psql
yaratabilirsiniz. PostgreSQL ayn<79> zamanda ODBC istemcileri ile
haberlesebilmektedir.
*Sunucu*
Veritaban<EFBFBD> sunuucsu Cygwin kullanarak Windows NT, 2K ya da XP <20>zerinde
calistirilabilir. Dag<61>t<EFBFBD>m i<>indeki pgsql/doc/FAQ_MSW<53>N dosyas<61>n<EFBFBD> ya da
web sitemizdeki MS Windows FAQ'u inceleyebilirsiniz.
Do<EFBFBD>al Windows NT/2000/XP portu i<>in <20>u anda <20>al<61><6C>malar devam etmektedir.
Windows s<>r<EFBFBD>m<EFBFBD> hakk<6B>nda g<>ncel bilgi i<>in,
http://techdocs.postgresql.org/guides/Windows adresini ziyaret
edebilirsiniz.
Ayr<EFBFBD>ca, http://forge.novell.com adresinde Novell Netware 6 portu
bulunmaktad<EFBFBD>r.
1.5) PostgreSQL'i nereden indirebilirim?
PostgreSQL i<>in ana anonim ftp sitesi ftp://ftp.PostgreSQL.org/pub' dur.
Yans<EFBFBD>lar i<>in, ana web sayfam<61>za bakabilirsiniz.
1.6) Nereden destek alabilirim?
Ana e-posta listesi : pgsql-general@PostgreSQL.org. PostgreSQL
konusundaki tart<72>smalara a<><61>kt<6B>r. <20>ye olmak i<>in, asag<61>daki sat<61>rlar<61>
e-postanizin body k<>sm<73>na (konu k<>sm<73>na degil) yaz<61>p,
pgsql-general-request@PostgreSQL.org adresine g<>nderin:
subscribe
end
Ayn<EFBFBD> zamanda, bir digest listesi bulunmaktad<61>r. Bu listeye <20>ye olmak
i<EFBFBD>in, pgsql-general-digest-request@PostgreSQL.org adresine, body k<>sm<73>nda
subscribe
end
yazan bir e-posta atman<61>z yeterli olacakt<6B>r.
Digest postalar, ana liste 30k civar<61>nda e-postaya ulastiginda <20>yelere
g<EFBFBD>nderilmektedir.
Buglar i<>in bir e-posta listesi bulunmaktad<61>r. Bu listeye <20>ye olmak
i<EFBFBD>in, email to pgsql-bugs-request@PostgreSQL.org adresine, body k<>sm<73>nda
subscribe
end
yazan bir e-posta atman<61>z yeterli olacakt<6B>r.
Ayn<EFBFBD> zamanda, gelistiriciler i<>in tart<72>sma listesi bulunmaktad<61>r. Bu
listeye <20>ye olmak i<>in, pgsql-hackers-request@PostgreSQL.org adresine,
body k<>sm<73>nda
subscribe
end
yazan bir e-posta atman<61>z yeterli olacakt<6B>r.
Bunun d<>s<EFBFBD>ndaki e-posta listelerine ve PostgreSQL hakk<6B>nda bilgiye,
PostgreSQL WWW ana sayfas<61>ndan ulasabilirsiniz:
http://www.PostgreSQL.org
Ayn<EFBFBD> zamanda, EFNet <20>zerinde, #PostgreSQL adl<64> bir <20>RC kanal<61>
bulunmaktad<EFBFBD>r. Bunun i<>in, irc -c '#PostgreSQL' "$USER" irc.phoenix.net
Unix komutunu kullanabilirsiniz.
Ticari destek veren firmalar<61>n listesine
http://www.postgresql.org/users-lounge/commercial-support.html
adresinden ulasabilirsiniz.
1.7) En son s<>r<EFBFBD>m nedir?
PostgreSQL'in son s<>r<EFBFBD>m<EFBFBD> 7.3.3't<>r.
Her 4 ayda major release <20><>kar<61>lmas<61> planlanmaktad<61>r.
1.8) Hangi belgelere ulasabilirim?
Da<EFBFBD><EFBFBD>t<EFBFBD>m<EFBFBD>n icinde, kitapciklar, kitapcik sayfalari ve bazi k<><6B><EFBFBD>k <20>rnekler
verilmektedir. /doc dizinine bak<61>n<EFBFBD>z. Ayrica, bu el kitap<61><70>klar<61>n<EFBFBD>
online olarak http://www.PostgreSQL.org/docs/ adresinden inceleyebilirsiniz.
http://www.PostgreSQL.org/docs/awbook.html ve
http://www.commandprompt.com/ppbook adreslerinde PostgreSQL kitaplar<61>
bulunmaktad<EFBFBD>r. PostgreSQL kitablar<61>n<EFBFBD>n listesine,
http://www.ca.PostgreSQL.org/books/ adresinden ula<6C>aiblirsiniz. Ayr<79>ca,
PostgreSQL konusundaki teknik makalelere de
http://techdocs.PostgreSQL.org/ adresinden ula<6C>abilirsiniz.
psql'in, \d ile baslayan veri tipler, operatorler, fonksiyonlar,
aggregateler, vb. ile ilgili g<>zel komutlar<61> vard<72>r.
Web sitemiz daha fazla belgeyi i<>ermektedir.
1.9) Bilinen hatalar ya da eksik <20>zelliklere nereden ulasabilirim?
PostgreSQL SQL-92 uyumlugugu icindedir, standartlardan fazla da
<EFBFBD>zellikleri bulunmaktad<61>r. Bilinen hatalar, eksik <20>zellikler ve gelecek
ile ilgili planlar i<>in TODO listesine bak<61>n<EFBFBD>z.
1.10) Nas<61>l SQL <20><>renebilirim?
http:/www.PostgreSQL.org/docs/awbook.html adresindeki kitap SQL
<EFBFBD>gretecektir. http://www.commandprompt.com/ppbook adresinde de bir baska
PostgreSQL kitab<61> bulunmaktad<61>r.
http://www.intermedia.net/support/sql/sqltut.shtm,
http://ourworld.compuserve.com/homepages/graeme_birchall/HTM_COOK.HTM
http://sqlcourse.com ve http://sqlcourse2.com adreslerinde de g<>zel
belgeler bulunmaktad<61>r.
Bir ba<62>kas<61> da, http://members.tripod.com/er4ebus/sql/index.htm
adresinde bulunan "Teach Yourself SQL in 21 Days, Second Edition" kitab<61>d<EFBFBD>r.
Baz<EFBFBD> kullan<61>c<EFBFBD>lar<61>m<EFBFBD>z da <20>u kitab<61> <20>nermektedirler: The Practical SQL
Handbook, Bowman, Judith S., et al.,Addison-Wesley. Others like The
Complete Reference SQL, Groff et al., McGraw-Hill.
1.11) PostgreSQL 2000 y<>l<EFBFBD>na uyumlu mudur?
Evet.
1.12) Gelistirme tak<61>m<EFBFBD>na nas<61>l kat<61>labilirim?
<EFBFBD>ncelikle, en son kaynak kodunu indirin ve web sitemizdeki ya da
dag<EFBFBD>t<EFBFBD>m<EFBFBD>n i<>indeki PostgreSQL Developer belgesini okuyun. Ardindan,
pgsql-hackers ve pgsql-patches listelerine <20>ye olun. <20><><EFBFBD>nc<6E> olarak da,
pgsql-pacthes listesine y<>ksek kalitede yamalar g<>nderin.
PostgreSQL CVS arsivine erisim izni olan, 10 kadar gelistirici
bulunmaktadir. Hepsi defalarca, diger kisilerin yaptigindan cok daha
y<EFBFBD>ksek-kaliteli patchler gondermislerdir. Ayrica biz de bu
gelistiricilerin ekledikleri yamalarin y<>ksek kalitede olduguna g<>veniyoruz.
1.13) Bir hata raporunu nas<61>l g<>nderebilirim?
PostgreSQL BugTool sayfasina gidiniz. O sayfada bir bug bildirmek icin
neleri yapman<61>z gerektigi anlatilmistir.
Ayr<EFBFBD>ca, ftp://ftp.PostgreSQL.org/pub ftp adresimizde, yeni bir
PostgreSQL s<>r<EFBFBD>m<EFBFBD> ya da yamasi olup olmadigini kontrol ediniz.
1.14) PostgreSQL, diger DBMS'lerle nas<61>l karsilast<73>r<EFBFBD>labilir?
Bir yazilimin g<>c<EFBFBD>n<EFBFBD> <20>l<EFBFBD>mek i<>in <20>esitli yollar vardir: Yazilimin
<EFBFBD>zellikleri, basar<61>m<EFBFBD>, g<>venilirligi, destegi ve <20>creti.
<EFBFBD>zellikler:
PostgreSQL mevcut b<>y<EFBFBD>k ticari veritabanlarinin, transaction, subselect,
trigger, view, foreign key referential integrity ve sophisticated
locking gibi (user-defined types), rules, inheritance ve lock
cak<EFBFBD>smalarini d<>s<EFBFBD>rmek icin multi-version uyumluluk <20>zellikleri
bulunmaktadir.
Performans (Ba<42>ar<61>m):
PostgreSQL, di<64>er ticari ve a<><61>k kaynak kodlu veritabanlar<61>yla yak<61>n
ba<EFBFBD>ar<EFBFBD>m<EFBFBD> sa<73>lar. Baz<61> a<><61>lardan daha h<>zl<7A>d<EFBFBD>r, di<64>er a<><61>lardan da
yava<EFBFBD>t<EFBFBD>r. MySQL ya da daha zay<61>f veritabanlar<61> ile
kar<EFBFBD><EFBFBD>la<EFBFBD>t<EFBFBD>r<EFBFBD>ld<EFBFBD><EFBFBD><EFBFBD>nda,insert/update islemlerinde, transaction bazl<7A>
<EFBFBD>al<EFBFBD>st<EFBFBD><EFBFBD><EFBFBD>m<EFBFBD>z i<>in daha yava<76><61>z. MySQL, yukar<61>daki "<22>zellikler" k<>sm<73>nda
belirtilenlerden hi<68> birine sahip de<64>ildir. Biz, ba<62>ar<61>m<EFBFBD>m<EFBFBD>z<EFBFBD> her
s<EFBFBD>r<EFBFBD>mde artt<74>rsak da, esneklik ve geli<6C>mi<6D> <20>zellikler i<>in yap<61>lanm<6E>s
durumday<EFBFBD>z . PostgreSQL'i MySQL ile kar<61><72>la<6C>t<EFBFBD>ran <20>u web sitesine
bakabilirsiniz: http://openacs.org/why-not-mysql.html
G<EFBFBD>venilirlik:
DBMSlerin g<>venilir olmas<61> gerketigi, yoksa degerleri olmayacagini
d<EFBFBD>s<EFBFBD>n<EFBFBD>yoruz <20>ok iyi test edilmis, dengeli <20>al<61>san minimum say<61>da hata
i<EFBFBD>eren kod sunmaya <20>al<61>s<EFBFBD>yoruz. Her bir s<>r<EFBFBD>m en az 1 ayl<79>k beta
testlerinden ge<67>irilmektedir. S<>r<EFBFBD>m ge<67>mi<6D>ine bakarsan<61>z, <20>retime haz<61>r,
dengeli ve kararl<72> kodlar sundugumuzu g<>rebilirsiniz. Bu alanda, diger
veritaban<EFBFBD> yaZ<61>l<EFBFBD>mlar<61>na <20>st<73>nl<6E>g<EFBFBD>m<EFBFBD>z olduguna inanmaktay<61>z
Destek:
E-posta listemiz, olusan herhangi bir sorunu <20><>zebilecek b<>y<EFBFBD>k say<61>da
kullan<EFBFBD>c<EFBFBD> ve gelistirici grubunu i<>erir. Sorununuz i<>in, en az bir
ticari veritaban<61> kadar rahat <20><>z<EFBFBD>m bulabilirsiniz. Gelistiricilere,
kullan<EFBFBD>c<EFBFBD> grubuna, belgelere ve kaynak koda direk olarak erisebilme,
PostgreSQL destegini, diger DBMSlere g<>re daha <20>nemli k<>lar. Gereksinimi
olanlara, ticari destek verilebilir. (Destek i<>in 1.6 b<>l<EFBFBD>m<EFBFBD>ne bak<61>n<EFBFBD>z.)
Fiyat:
Ticari ve ticari olmayan t<>m kullan<61>mlar<61>n<EFBFBD>z i<>in PostgreSQL
<EFBFBD>cretsizdir. Kodumuzu, yukar<61>da belirtilen BSD-stili lisanstaki
s<EFBFBD>n<EFBFBD>rlamalar hari<72>, <20>r<EFBFBD>n<EFBFBD>n<EFBFBD>z<EFBFBD>n i<>ine ekleyebilirsiniz.
1.15) PostgreSQL'e maddi a<><61>dan nas<61>l destek olabilirim?
PostgreSQL, 1996 y<>l<EFBFBD>ndan beri 1.s<>n<EFBFBD>f altyap<61>ya ashiptir. Bunun i<>in,
y<EFBFBD>llar boyu <20>al<61>s<EFBFBD>p bu altyap<61>y<EFBFBD> olusturup y<>neten Marc Fournier'e
tesekk<EFBFBD>rler.
Bir a<><61>k kaynak kodlu proje i<>in, kaliteli altyap<61> <20>ok <20>nemlidir. Bu
altyap<EFBFBD>, projenin kesilmesini <20>nler ve projenin ilerlemesini h<>zland<6E>r<EFBFBD>r.
Tabii ki bu altyap<61> ucuz degildir. <20>slerin y<>r<EFBFBD>mesi i<>in <20>e<EFBFBD>itli y<>l<EFBFBD>k
ve anl<6E>k harcamalar<61>m<EFBFBD>z olmaktad<61>r. Eger siz ya da sirketinizin bu
<EFBFBD>abam<EFBFBD>za bag<61>sta bulunabilecek paras<61> varsa, l<>tfen
http://www.pgsql.com/pg_goodies adresine gidiniz ve bag<61>sta, hibede
bulununuz.
Web sayfas<61>n<EFBFBD>n PostgreSQL, <20>nc.' den bahsetmesine ragmen, "katk<74>da
bulunanlar" (contributors) maddesi sadece PostgreSQL projesini
desteklemek i<>indir ve belirli bir sirketin para kaynag<61> degildir.
isterseniz, baglant<6E> adresine bir <20>ek g<>nderebilirsiniz.
------------------------------------------------------------------------
Kullan<61>c<EFBFBD>/istemci Sorular<61>
2.1) PostgreSQL icin ODBC s<>r<EFBFBD>c<EFBFBD>leri var m<>?
iki tane ODBC s<>r<EFBFBD>c<EFBFBD>s<EFBFBD> bulunmaktad<61>r: PsqlODBC ve OpenLink ODBC.
PsqlODBC'i http://gborg.postgresql.org/project/psqlodbc/projdisplay.php
adresinden indirebilirsiniz.
OpenLink ODBC http://www.openlinksw.com adresinden al<61>nabilir.Bu s<>r<EFBFBD>c<EFBFBD>,
kendi standart ODBC istemci yaz<61>l<EFBFBD>m<EFBFBD> ile <20>al<61>st<73><74><EFBFBD>ndan, destekledikleri
her platformda (Win, Mac, Unix, VMS) PostgreSQL ODBC bulunmalidir.
<EFBFBD>cretsiz s<>r<EFBFBD>m<EFBFBD> olmakla beraber, ticari kalitede destek almak
isteyenlere satmak isteyeceklerdir. Sorular<61>n<EFBFBD>z<EFBFBD> l<>tfen
postgres95@openlink.co.uk adresine g<>nderiniz.
2.2) PostgreSQL'i web sayfalar<61>nda kullanabilmek i<>in hangi
ara<72>lar bulunmaktad<61>r?
http://www.webreview.com adresinde, arka planda veritaban<61> <20>al<61>st<73>ran
Web sayfalar<61> i<>in giris seviyesinde bilgi bulunmaktad<61>r.
Web ile b<>t<EFBFBD>nlesme i<>in, PHP m<>kemmel bir arabirim sunar. http://www.php.net
Karma<EFBFBD><EFBFBD>k sorunlar i<>in, <20>o<EFBFBD>u kisi Perl arabirimini ve CGI.pm ya da
mod_perl kullan<61>r.
2.3) PostgreSQL'in grafik kullan<61>c<EFBFBD> arabirimi var m<>d<EFBFBD>r?
<EFBFBD>e<EFBFBD>itli grafik arabirimlerimiz bulunmaktad<61>r. Bunlar<61>n aras<61>nda,
PgAccess (http://www.pgaccess.org), PgAdmin II (http://www.pgadmin.org,
sadece Win32 i<>in), RHDB Admin (http://sources.redhat.com/rhdb/ ) ve
Rekall (http://www.thekompany.com/products/rekall/) bulunmaktad<61>r.
Ayr<EFBFBD>ca, PostgreSQL i<>in web tabanl<6E> bir arabirim olan PHPPgAdmin (
http://phppgadmin.sourceforge.net/ ) bulunmaktad<61>r.
Daha ayr<79>nt<6E>l<EFBFBD> liste i<>in http://techdocs.postgresql.org/guides/GUITools
adresine bakabilirsiniz.
2.4) PostgreSQL ile ileti<74>imi kurabilmek i<>in hangi dilleri
kullanabilirim?
* C (libpq)
* Embedded C (ecpg)
* Java (jdbc)
* Python (PyGreSQL)
* TCL (libpgtcl)
Di<EFBFBD>erleri i<>in, http://gborg.postgresql.org adresindeki
Drivers/Interfaces b<>l<EFBFBD>m<EFBFBD>ne bakabilirsiniz.
------------------------------------------------------------------------
Y<>netimsel Sorular
3.1) PostgreSQL'i, /usr/local/pgsql dizininden baska dizinlere
nas<61>l kurabilirim?
configure betigini <20>al<61>st<73>r<EFBFBD>rken, --prefix se<73>enegini veriniz.
3.2) postmaster'i baslatt<74>g<EFBFBD>mda, a Bad System Call ya da core
dumped mesaj<61> al<61>yorum. Neden?
Bunun bir<69>ok nedeni olabilir. Ancak ilk kontrol edilmesi gereken sey,
<EFBFBD>ekirdeginize System V uzant<6E>lar<61>n<EFBFBD>n kurulu olup olmad<61>g<EFBFBD>n<EFBFBD> kontrol
etmek olabilir. PostgreSQL shared memory ve semaphores i<>in <20>ekirdek
destegine gereksinim duyar.
3.3) postmaster'i baslatt<74>g<EFBFBD>mda, a <20>pcMemoryCreate hatas<61>
al<61>yorum. Neden?
Ya <20>ekirdeginizde shared memory desteginiz d<>zg<7A>nce
yap<EFBFBD>land<EFBFBD>r<EFBFBD>lmam<EFBFBD>st<EFBFBD>r, ya da <20>ekirdeginizdeki mevcut shared memory
miktar<EFBFBD>n<EFBFBD> b<>y<EFBFBD>tmeniz gerekecektir. Gereksinim duyacag<61>n<EFBFBD>z miktar,
mimarinize ve postmaster i<>in ayarlad<61>g<EFBFBD>n<EFBFBD>z tampon ile backend islemi
say<EFBFBD>s<EFBFBD>na bagl<67>d<EFBFBD>r. T<>m sistemler i<>in, tamponlar ve islemlerde <20>ntan<61>ml<6D>
say<EFBFBD>larla, ~ 1MB kadar yere gereksinmeniz olacaktir.PostgreSQL
Administrator's Guide' a, shared memory ve semaphorelar hakk<6B>ndaki
ayr<EFBFBD>nt<EFBFBD>l<EFBFBD> bilgi i<>in bakabilirsiniz.
3.4) postmaster'i baslatt<74>g<EFBFBD>mda, a <20>pcSemaphoreCreate hatas<61>
al<61>yorum. Neden?
Eger hata, "<22>pcSemaphoreCreate: semget failed (No space left on device)"
ise, <20>ekirdeginiz yeterli semaphore ile yap<61>land<6E>r<EFBFBD>lmam<61>s demektir.
Postgres, her bir potansiyel backend i<>in bir semaphore gereksinmesi
duyar. Ge<47>ici bir <20><>z<EFBFBD>m, postmaster<65> backend islemleri i<>in daha az
miktarda s<>n<EFBFBD>rla baslatmak olabilir. -N i varsa<73>lan deger olan 32'den
k<EFBFBD><EFBFBD><EFBFBD>k bir degerle baslat<61>n<EFBFBD>z. Daha kal<61>c<EFBFBD> bir <20><>z<EFBFBD>m, <20>ekirde<64>inizin
SEMMNS ve SEMMNI parametrelerini y<>kseltmek olacakt<6B>r.
<EFBFBD>al<EFBFBD><EFBFBD>mayan semaphorelar a<><61>r veritaban<61> islemlerinde <20><>kme yaratabilirler.
Eger hata mesaj<61>n<EFBFBD>z baska birsey ise, <20>ekirdeginizde semaphore destegini
yap<EFBFBD>land<EFBFBD>rmam<EFBFBD>s olabilirsiniz. Shared memory ve semaphorelar hakk<6B>ndaki
daha ayr<79>nt<6E>l<EFBFBD> bilgi i<>in PostgreSQL Administrator's Guide'a bakabilirsiniz.
3.5) Diger bilgisayarlar<61>n benim PostgreSQL veritaban<61> sunucuma
baglant<6E>lar<61>n<EFBFBD> nas<61>l kontrol edebilirim?
<EFBFBD>n tan<61>ml<6D> olarak, PostgreSQL sadece yerel makineden Unix domain sockets
kullanarak baglan<61>lmas<61>na izin verir. Diger makineler, postmaster'a -i
etiketini ge<67>irmezseniz ve $PGDATA_pg_hba.conf dosyas<61>n<EFBFBD> d<>zenleyerek
host-based authentication'a olanak vermezseniz, baglant<6E> yapamayacaklard<72>r.
3.6) Veritabani motorunu daha iyi basarim icin nasil
ayarlayabilirim?
Indexler sorgular<61> h<>zland<6E>rabilir. EXPLAIN komutu, PostgreSQL'in
sorgunuzu nas<61>l yorumlad<61><64><EFBFBD>n<EFBFBD> ve hangi indexleri kullandigini g<>rmenize
izin verir.
E<EFBFBD>er cok fazla INSERT islemi yapiyorsaniz, bunlar<61> b<>y<EFBFBD>k bir toplu islem
dosyasi kullan<61>p COPY komutu ile veritabanina girmeyi deneyiniz. Bu,
tekil <20>NSERTlerden daha h<>zl<7A>d<EFBFBD>r. ikinci olarak, BEG<45>N WORK/COMM<4D>T
transaction blogu i<>inde olmayan ifadeler kendi transactionlarindaymis
gibi d<>s<EFBFBD>n<EFBFBD>l<EFBFBD>r. <20>oklu ifadeleri tek bir transaction blo<6C>u i<>inde
yapabilirsiniz. Bu, transaction overheadini d<><64><EFBFBD>recektir. Tek bir
transaction blo<6C>u i<>inde birden <20>ok ifadeyi <20>al<61><6C>t<EFBFBD>rmay<61>
deneyebilirsiniz. Bu, transaction overhead ini d<><64><EFBFBD>r<EFBFBD>r.
<EFBFBD>e<EFBFBD>itli ayarlama se<73>enekleri mevcuttur. fsync() i<>lemini, postmaster'<27>
-o -F se<73>ene<6E>i ile ba<62>latarak devre d<><64><EFBFBD> b<>rakabilirsiniz. Bu i<>lem,
fsync()'lerin her transactiondan sonra diske flush etmesini engelleyecektir.
Ayn<EFBFBD> zamanda, postmaster'i -B se<73>ene<6E>i ile ba<62>lat<61>p, backend i<>lemleri
taraf<EFBFBD>ndan kullan<61>lan shared memorf buffers say<61>lar<61>n<EFBFBD>
artt<EFBFBD>rabilirsiniz. Eger bu parametreyi <20>ok y<>ksek tutarsan<61>z,
<EFBFBD>ekirde<EFBFBD>inizin shared memory b<>lgesindeki limiti a<>ma olas<61>l<EFBFBD><6C><EFBFBD>n<EFBFBD>z
y<EFBFBD>z<EFBFBD>nden postmaster ba<62>layamayabilir. Her bir tampon (buffer) 8K'd<>r.
<EFBFBD>ntan<EFBFBD>ml<EFBFBD> say<61> ise 64 tampondur.
Ayn<EFBFBD> <20>ekilde, backend'in -S se<73>ene<6E>ini ge<67>ici s<>ralamalar i<>in backend
s<EFBFBD>re<EFBFBD>leri taraf<61>ndan kullan<61>lacak haf<61>zay<61> artt<74>rmak amac<61>yla
kullanabilirsiniz. -S se<73>ene<6E>i kilobayt cinsinden de<64>er al<61>r ve <20>n
tan<EFBFBD>ml<EFBFBD> de<64>eri 512'dir (512 K)
Tablolardaki veriyi bir indekse e<>lemek amac<61>yla gruplama i<>in CLUSTER
komutunu kullanabilirsiniz. Ayr<79>nt<6E>l<EFBFBD> bilgi i<>in CLUSTER komutunun
yard<EFBFBD>m sayfas<61>na bakabilirsiniz.
3.7) Hangi hata ay<61>klama <20>zellikleri bulunmaktad<61>r?
PostgreSQL, hata ay<61>klama amac<61>yla kullan<61>labilecek durum bilgisi rapor
eden <20>e<EFBFBD>itli <20>zeliklere sahiptir.
<EFBFBD>ncelikle, configure beti<74>ini --enable-cassert se<73>ene<6E>iyle
<EFBFBD>al<EFBFBD><EFBFBD>t<EFBFBD>r<EFBFBD>rsan<EFBFBD>z, bir <20>ok assert() backend cal<61><6C>mas<61>n<EFBFBD> g<>zlemler ve
beklenmeyen bir durumda program<61> durdurur.
Postmaster ve postgres <20>e<EFBFBD>itli hata ay<61>klama se<73>eneklerine sahiptir.
<EFBFBD>ncelikle, postmaster'i ba<62>latt<74><74><EFBFBD>n<EFBFBD>zda, standart <20><>kt<6B>y<EFBFBD> ve hatalar<61>
bir log dosyas<61>na y<>nlendirdi<64>inize emin olun:
cd /usr/local/pgsql
./bin/postmaster >server.log 2>&1 &
Bu i<>lem PostgreSQL ana dizinine server.log dosyas<61> yerle<6C>tirecektir. Bu
dosya sunucunun ya<79>ad<61><64><EFBFBD> sorunlar ya da hatalar hakk<6B>nda yararl<72>
bilgiler i<>erir. -d se<73>ene<6E>i, hata ay<61>klama seviyesini belirten bir
rakam ile kullan<61>l<EFBFBD>r. Y<>ksek hata ay<61>klama seviyelerinin b<>y<EFBFBD>k log
dosyalar<EFBFBD> olu<6C>turaca<63><61>n<EFBFBD> unutmay<61>n<EFBFBD>z.
E<EFBFBD>er postmaster <20>al<61><6C>m<EFBFBD>yorsa, postgres backend'ini komut sat<61>r<EFBFBD>ndan
<EFBFBD>al<EFBFBD><EFBFBD>t<EFBFBD>rabilir ve SQL ifadenizi direk olarak yazabilirsiniz. Bu sadece
hata ay<61>klama amac<61>yla <20>nerilir. Burada, noktal<61> virg<72>l<EFBFBD>n de<64>il de yeni
bir sat<61>r<EFBFBD>n sorguyu sonland<6E>rd<72><64><EFBFBD>n<EFBFBD> unutmay<61>n<EFBFBD>z. E<>er hata ay<61>klama
sembolleri ile derlediyseniz, ne oldu<64>unu g<>rmek i<>in bir hata
ay<EFBFBD>klay<EFBFBD>c<EFBFBD> kullanabilirsiniz. backend postmasterdan ba<62>lat<61>lmad<61><64><EFBFBD>ndan,
e<EFBFBD>de<EFBFBD>er bir ortamda <20>al<61><6C>mamaktad<61>r ve locking/backend etkile<6C>im
sorunlar<EFBFBD> artabilir.
E<EFBFBD>er postmaster <20>al<61><6C><EFBFBD>yorsa, bir pencerede psql'i <20>al<61><6C>t<EFBFBD>r<EFBFBD>n ve psql
taraf<EFBFBD>ndan kullan<61>lan postgres s<>recinin s<>re<72> numaras<61>n<EFBFBD> (PID) bulun.
Postgres s<>reci ile ili<6C>kilendirmek i<>in bir hata ay<61>klar<61>c<EFBFBD> kullan<61>n.
Sorgular<EFBFBD> psql arac<61>l<EFBFBD><6C><EFBFBD> ile <20>al<61><6C>t<EFBFBD>rabilirsiniz. E<>er postgres
ba<EFBFBD>lang<EFBFBD>c<EFBFBD>nda hata ay<61>klamak istiyorsan<61>z, PGOPTIONS="-W n" se<73>ene<6E>ini
ayarlayabilir ve psql'i ba<62>latabilirsiniz. Bu i<>lem, ba<62>lang<6E>c<EFBFBD>n n
saniye kadar gecikmesini sa<73>layacakt<6B>r; b<>ylece hata ay<61>klay<61>c<EFBFBD>y<EFBFBD> s<>rece
ili<EFBFBD>kilendirdikten sonra ba<62>lang<6E><67> s<>recinin devam etmesini
sa<EFBFBD>layabilirsiniz.
postgres program<61> hata ay<61>klama ve ba<62>ar<61>m <20>l<EFBFBD><6C>mleri i<>in -s, -A ve -t
se<EFBFBD>eneklerine sahiptir.
3.8) Baglanmaya <20>al<61>s<EFBFBD>ken, neden "Sorry, too many clients"
hatas<61>n<EFBFBD> al<61>yorum?
Postmaster'in e<>zamanl<6E> olarak ba<62>latabilece<63>i backend s<>re<72>leri
s<EFBFBD>n<EFBFBD>rlar<EFBFBD>n<EFBFBD> artt<74>rman<61>z gerekmektedir.
<EFBFBD>n tan<61>ml<6D> de<64>er 32 s<>re<72>tir. Bunu, postmaster'i uygun -N de<64>eri ile ya
da postgresql.conf dosyas<61>n<EFBFBD> d<>zenleyerek yeniden ba<62>latmakla
artt<EFBFBD>rabilirsiniz.
E<EFBFBD>er -N de<64>erini 32'den b<>y<EFBFBD>k yapacaksan<61>z, ayn<79> zamanda -B de<64>erini de
de<EFBFBD>i<EFBFBD>tirmeniz gerekti<74>ini unutmay<61>n. -B -N'nin en az 2 kat<61> kadar
olmal<EFBFBD>d<EFBFBD>r; daha iyi ba<62>ar<61>m i<>in bu say<61>y<EFBFBD> daha da artt<74>rmal<61>s<EFBFBD>n<EFBFBD>z.
Y<EFBFBD>ksek say<61>daki backend s<>re<72>leri i<>in, <20>e<EFBFBD>itli <20>ekirdek yap<61>land<6E>rma
parametrelerini artt<74>rman<61>z gerekecektir. Yap<61>lmas<61> gerekenler, SHMMAX,
SEMMNS, SEMMNI, NPROC, MAXUPRC ve a<><61>labilecek dosyalar<61>n maksimum
say<EFBFBD>s<EFBFBD> olan NFILE ve NINODE de<64>erlerini kar<61><72>t<EFBFBD>rmakt<6B>r. Bunun nedeni,
PostgreSQL'in izin verilen backend s<>re<72>lerinin say<61>s<EFBFBD> <20>zerinde bir
s<EFBFBD>n<EFBFBD>r<EFBFBD> olmas<61>d<EFBFBD>r. B<>ylelikle sistem kaynaklar<61>n<EFBFBD>n d<><64><EFBFBD>na <20><>k<EFBFBD>lmayacakt<6B>r.
PostgreSQL'in 6.5 s<>r<EFBFBD>m<EFBFBD>ne kadar, en fazla backend say<61>s<EFBFBD> 64 idi ve bunu
de<EFBFBD>i<EFBFBD>tirmek i<>in include/storage/sinvaladt.h dosyas<61> i<>indeki
MaxBAckendid sabitini de<64>i<EFBFBD>tirdek sonra yaz<61>l<EFBFBD>m<EFBFBD> yeniden derlemek
gerekiyordu.
3.9) pgsql_tmp dizinin i<>indeki dosyalar nelerdir?
Sorgu <20>al<61>st<73>r<EFBFBD>c<EFBFBD> (query executer) taraf<61>ndan yarat<61>lan ge<67>ici
dosyalard<EFBFBD>r. <20>rnegin, bir s<>ralama ORDER BY ile yapilacaksa ve s<>ralama
backend'in -s parametresinin izin verdiginden daha fazla alana
gereksinim duyuyorsa, ekstra veriyi tutmak i<>in ge<67>ici dosyalar yarat<61>l<EFBFBD>r.
Ge<EFBFBD>ici dosyalar, eger s<>ralama s<>ras<61>nda backend g<><67>mezse otomatik
olarak silinecektir. Eger <20>al<61>san durumda bir backendiniz yoksa,
pg_tempNNN.NN dosyalar<61>n<EFBFBD> silmeniz g<>venlidir..
3.10) PostgreSQL s<>r<EFBFBD>mlerini y<>kselmek i<>in neden bir
dump/reload i<>lemi ger<65>ekle<6C>tirmek zorunday<61>m?
PostgreSQL tak<61>m<EFBFBD> ara s<>r<EFBFBD>mlerde sadece k<><6B><EFBFBD>k de<64>i<EFBFBD>iklikler yapmaktad<61>r;
bu y<>zden 7.2 s<>r<EFBFBD>m<EFBFBD>nden 7.2.1'e y<>kseltmek dump/restore i<>lemi
gerekmemektedir. Ancak, esas s<>r<EFBFBD>mlerde (<28>rnek: 7.2'den 7.3'e)
<EFBFBD>o<EFBFBD>unlukla sistem tablolar<61>n<EFBFBD>n ve veri dosyalar<61>n<EFBFBD>n i<> yap<61>s<EFBFBD>
de<EFBFBD>i<EFBFBD>tirilir. Bu de<64>i<EFBFBD>iklikler <20>o<EFBFBD>unlukla karma<6D><61>kt<6B>r; dolay<61>s<EFBFBD>yla veri
dosyalar<EFBFBD>n<EFBFBD>n geriye d<>n<EFBFBD>k uyumlulu<6C>u i<>lemlerini yapm<70>yoruz. Dump
i<EFBFBD>lemi, veriyi genel bi<62>imde alaca<63><61>ndan yeniden y<>kleme esnas<61>nda veri,
yeni i<> bi<62>ime uygun <20>ekilde yerle<6C>tirilecektir.
Disk bi<62>iminin de<64>i<EFBFBD>medi<64>i s<>r<EFBFBD>mlerde, pg_upgrade beti<74>i g<>ncellemenin
bir dump/restore gerektirmeden yap<61>lmas<61>n<EFBFBD> sa<73>layacakt<6B>r. pg_upgrade
beti<EFBFBD>inin o s<>r<EFBFBD>m i<>in bulunup bulunmad<61><64><EFBFBD>n<EFBFBD> s<>r<EFBFBD>m notlar<61> i<>inde
bulabilirsiniz.
------------------------------------------------------------------------
<20><>letimsel Sorular
4.1) Binary cursor ve normal cursor arasindaki fark nedir?
DECLARE yard<72>m sayfasina bakiniz.
4.2) Sorgunun sadece ilk birka<6B> sat<61>r<EFBFBD>n<EFBFBD> nasil SELECT edebilirim?
FETCH yard<72>m sayfasina bakiniz, aya da SELECT ... LIMIT.... kullan<61>n<EFBFBD>z.
The entire query may have to be evaluated, even if you only want the
first few rows. Consider a query that has an ORDER BY. <20>f there is an
index that matches the ORDER BY, PostgreSQL may be able to evaluate only
the first few records requested, or the entire query may have to be
evaluated until the desired rows have been generated.
4.3) psql'in i<>inde g<>rd<72>g<EFBFBD>m tablolarin ya da diger seylerin
listesini nasil alabilirim?
pgsql/src/bin/psql/describe.c i<>indeki psql kaynak kodunu
okuyabilirsiniz. Bu kod, psql'in \ ile baslayan komutlar<61>n<EFBFBD>n <20><>kt<6B>s<EFBFBD>n<EFBFBD>
olusturan SQL komutlarini i<>erir. Ayn<79> zamanda, psql'i -E se<73>ene<6E>i ile
ba<EFBFBD>lat<EFBFBD>p, verdi<64>iniz komutlar<61> <20>al<61><6C>t<EFBFBD>rmak i<>in yapt<70><74><EFBFBD> sorgular<61>n
<EFBFBD><EFBFBD>kt<EFBFBD>lar<EFBFBD>n<EFBFBD> g<>rebilirsiniz.
4.4) Bir tablodan bir kolonu nas<61>l kald<6C>rabilirim?
Bu <20>zellik (ALTER TABLE DROP COLUMN) 7.3 s<>r<EFBFBD>m<EFBFBD> ile gelmi<6D>tir. Eski
s<EFBFBD>r<EFBFBD>mlerde a<>a<EFBFBD><61>dakileri uygulamal<61>s<EFBFBD>n<EFBFBD>z:
BEGIN;
LOCK TABLE old_table;
SELECT ... -- select all columns but the one you want to remove
INTO TABLE new_table
FROM old_table;
DROP TABLE old_table;
ALTER TABLE new_table RENAME TO old_table;
COMMIT;
4.5) Bir sat<61>r, tablo ve veritaban<61> icin en fazla b<>y<EFBFBD>kl<6B>k nedir?
S<EFBFBD>n<EFBFBD>rlar:
Veritabani icin en fazla b<>y<EFBFBD>kl<6B>k nedir?
S<EFBFBD>n<EFBFBD>rs<EFBFBD>z (4 TB'l<>k veritaban<61> bulunmaktad<61>r)
Bir tablo icin en fazla b<>y<EFBFBD>kl<6B>k nedir?
16 TB
Bir sat<61>r i<>in en fazla b<>y<EFBFBD>kl<6B>k nedir?
1.6 TB
Bir alan i<>in en fazla b<>y<EFBFBD>kl<6B>k nedir?
1 GB
Tabloda en fazla sat<61>r say<61>s<EFBFBD> ka<6B>t<EFBFBD>r?
S<EFBFBD>n<EFBFBD>rs<EFBFBD>z
Bir tabloda olabilecek en fazla kolon say<61>s<EFBFBD> ka<6B>t<EFBFBD>r?
Kolon tiplerine ba<62>l<EFBFBD> olarak 250-1600
Bir tabloda olabilecek en fazla index say<61>s<EFBFBD> ka<6B>t<EFBFBD>r?
s<EFBFBD>n<EFBFBD>rs<EFBFBD>z
These are the limits:
Maximum size for a database? unlimited (4 TB databases exist)
Maximum size for a table? 16 TB
Maximum size for a row? 1.6TB
Maximum size for a field? 1 GB
Maximum number of rows in a table? unlimited
Maximum number of columns in a table? 250-1600 depending on column types
Maximum number of indexes on a table? unlimited
Of course, these are not actually unlimited, but limited to available
disk space and memory/swap space. Performance may suffer when these
values get unusually large.
The maximum table size of 16 TB does not require large file support from
the operating system. Large tables are stored as multiple 1 GB files so
file system size limits are not important.
The maximum table size and maximum number of columns can be increased if
the default block size is increased to 32k.
4.6) How much database disk space is required to store data from
a typical text file?
A PostgreSQL database may require up to five times the disk space to
store data from a text file.
As an example, consider a file of 100,000 lines with an integer and text
description on each line. Suppose the text string avergages twenty bytes
in length. The flat file would be 2.8 MB. The size of the PostgreSQL
database file containing this data can be estimated as 6.4 MB:
36 bytes: each row header (approximate)
24 bytes: one int field and one text field
+ 4 bytes: pointer on page to tuple
----------------------------------------
64 bytes per row
The data page size in PostgreSQL is 8192 bytes (8 KB), so:
8192 bytes per page
------------------- = 128 rows per database page (rounded down)
64 bytes per row
100000 data rows
-------------------- = 782 database pages (rounded up)
128 rows per page
782 database pages * 8192 bytes per page = 6,406,144 bytes (6.4 MB)
Indexes do not require as much overhead, but do contain the data that is
being indexed, so they can be large also.
NULLs are stored in bitmaps, so they use very little space.
4.7) How do I find out what tables, indexes, databases, and
users are defined?
/psql/ has a variety of backslash commands to show such information. Use
\? to see them. There are also system tables beginning with /pg_/ that
describe these too. Also, /psql -l/ will list all databases.
Also try the file /pgsql/src/tutorial/syscat.source/. It illustrates
many of the SELECTs needed to get information from the database system
tables.
4.8) My queries are slow or don't make use of the indexes. Why?
Indexes are not automatically used by every query. Indexes are only used
if the table is larger than a minimum size, and the query selects only a
small percentage of the rows in the table. This is because the random
disk access caused by an index scan can be slower than a straight read
through the table, or sequential scan.
To determine if an index should be used, PostgreSQL must have statistics
about the table. These statistics are collected using VACUUM ANALYZE, or
simply ANALYZE. Using statistics, the optimizer knows how many rows are
in the table, and can better determine if indexes should be used.
Statistics are also valuable in determining optimal join order and join
methods. Statistics collection should be performed periodically as the
contents of the table change.
Indexes are normally not used for ORDER BY or to perform joins. A
sequential scan followed by an explicit sort is usually faster than an
index scan of a large table.
However, LIMIT combined with ORDER BY often will use an index because
only a small portion of the table is returned. In fact, though MAX() and
MIN() don't use indexes, it is possible to retrieve such values using an
index with ORDER BY and LIMIT:
SELECT col
FROM tab
ORDER BY col [ DESC ]
LIMIT 1;
If you believe the optimizer is incorrect in choosing a sequential scan,
use |SET enable_seqscan TO 'off'| and run tests to see if an index scan
is indeed faster.
When using wild-card operators such as LIKE or /~/, indexes can only be
used in certain circumstances:
* The beginning of the search string must be anchored to the start
of the string, i.e.
o LIKE patterns must not start with /%/.
o /~/ (regular expression) patterns must start with /^/.
* The search string can not start with a character class, e.g. [a-e].
* Case-insensitive searches such as ILIKE and /~*/ do not utilise
indexes. Instead, use functional indexes, which are described in
section 4.12 <#4.12>.
* The default /C/ locale must be used during /initdb/.
4.9) How do I see how the query optimizer is evaluating my query?
See the EXPLAIN manual page.
4.10) What is an R-tree index?
An R-tree index is used for indexing spatial data. A hash index can't
handle range searches. A B-tree index only handles range searches in a
single dimension. R-trees can handle multi-dimensional data. For
example, if an R-tree index can be built on an attribute of type
/point/, the system can more efficiently answer queries such as "select
all points within a bounding rectangle."
The canonical paper that describes the original R-tree design is:
Guttman, A. "R-trees: A Dynamic Index Structure for Spatial Searching."
Proceedings of the 1984 ACM SIGMOD Int'l Conf on Mgmt of Data, 45-57.
You can also find this paper in Stonebraker's "Readings in Database
Systems".
Built-in R-trees can handle polygons and boxes. In theory, R-trees can
be extended to handle higher number of dimensions. In practice,
extending R-trees requires a bit of work and we don't currently have any
documentation on how to do it.
4.11) What is the Genetic Query Optimizer?
The GEQO module speeds query optimization when joining many tables by
means of a Genetic Algorithm (GA). It allows the handling of large join
queries through nonexhaustive search.
4.12) How do I perform regular expression searches and
case-insensitive regular expression searches? How do I use an
index for case-insensitive searches?
The /~/ operator does regular expression matching, and /~*/ does
case-insensitive regular expression matching. The case-insensitive
variant of LIKE is called ILIKE.
Case-insensitive equality comparisons are normally expressed as:
SELECT *
FROM tab
WHERE lower(col) = 'abc';
This will not use an standard index. However, if you create a functional
index, it will be used:
CREATE INDEX tabindex ON tab (lower(col));
4.13) In a query, how do I detect if a field is NULL?
You test the column with IS NULL and IS NOT NULL.
4.14) What is the difference between the various character types?
Type Internal Name Notes
--------------------------------------------------
VARCHAR(n) varchar size specifies maximum length, no padding
CHAR(n) bpchar blank padded to the specified fixed length
TEXT text no specific upper limit on length
BYTEA bytea variable-length byte array (null-byte safe)
"char" char one character
You will see the internal name when examining system catalogs and in
some error messages.
The first four types above are "varlena" types (i.e., the first four
bytes on disk are the length, followed by the data). Thus the actual
space used is slightly greater than the declared size. However, these
data types are also subject to compression or being stored out-of-line
by TOAST, so the space on disk might also be less than expected.
VARCHAR(n) is best when storing variable-length strings and it limits
how long a string can be. TEXT is for strings of unlimited length, with
a maximum of one gigabyte.
CHAR(n) is for storing strings that are all the same length. CHAR(n)
pads with blanks to the specified length, while VARCHAR(n) only stores
the characters supplied. BYTEA is for storing binary data, particularly
values that include NULL bytes. All the types described here have
similar performance characteristics.
4.15.1) How do I create a serial/auto-incrementing field?
PostgreSQL supports a SERIAL data type. It auto-creates a sequence and
index on the column. For example, this:
CREATE TABLE person (
id SERIAL,
name TEXT
);
is automatically translated into this:
CREATE SEQUENCE person_id_seq;
CREATE TABLE person (
id INT4 NOT NULL DEFAULT nextval('person_id_seq'),
name TEXT
);
CREATE UNIQUE INDEX person_id_key ON person ( id );
See the /create_sequence/ manual page for more information about
sequences. You can also use each row's /OID/ field as a unique value.
However, if you need to dump and reload the database, you need to use
/pg_dump/'s /-o/ option or COPY WITH OIDS option to preserve the OIDs.
4.15.2) How do I get the value of a SERIAL insert?
One approach is to retrieve the next SERIAL value from the sequence
object with the /nextval()/ function /before/ inserting and then insert
it explicitly. Using the example table in 4.15.1 <#4.15.1>, an example
in a pseudo-language would look like this:
new_id = execute("SELECT nextval('person_id_seq')");
execute("INSERT INTO person (id, name) VALUES (new_id, 'Blaise Pascal')");
You would then also have the new value stored in |new_id| for use in
other queries (e.g., as a foreign key to the |person| table). Note that
the name of the automatically created SEQUENCE object will be named
</table/>_</serialcolumn/>_/seq/, where /table/ and /serialcolumn/ are
the names of your table and your SERIAL column, respectively.
Alternatively, you could retrieve the assigned SERIAL value with the
/currval()/ function /after/ it was inserted by default, e.g.,
execute("INSERT INTO person (name) VALUES ('Blaise Pascal')");
new_id = execute("SELECT currval('person_id_seq')");
Finally, you could use the OID <#4.16> returned from the INSERT
statement to look up the default value, though this is probably the
least portable approach. In Perl, using DBI with Edmund Mergl's DBD::Pg
module, the oid value is made available via /$sth->{pg_oid_status}/
after /$sth->execute()/.
4.15.3) Don't /currval()/ and /nextval()/ lead to a race
condition with other users?
No. /currval()/ returns the current value assigned by your backend, not
by all users.
4.15.4) Why aren't my sequence numbers reused on transaction
abort? Why are there gaps in the numbering of my sequence/SERIAL
column?
To improve concurrency, sequence values are given out to running
transactions as needed and are not locked until the transaction
completes. This causes gaps in numbering from aborted transactions.
4.16) What is an OID? What is a TID?
OIDs are PostgreSQL's answer to unique row ids. Every row that is
created in PostgreSQL gets a unique OID. All OIDs generated during
/initdb/ are less than 16384 (from /include/access/transam.h/). All
user-created OIDs are equal to or greater than this. By default, all
these OIDs are unique not only within a table or database, but unique
within the entire PostgreSQL installation.
PostgreSQL uses OIDs in its internal system tables to link rows between
tables. These OIDs can be used to identify specific user rows and used
in joins. It is recommended you use column type OID to store OID values.
You can create an index on the OID field for faster access.
OIDs are assigned to all new rows from a central area that is used by
all databases. If you want to change the OID to something else, or if
you want to make a copy of the table, with the original OIDs, there is
no reason you can't do it:
CREATE TABLE new_table(old_oid oid, mycol int);
SELECT old_oid, mycol INTO new FROM old;
COPY new TO '/tmp/pgtable';
DELETE FROM new;
COPY new WITH OIDS FROM '/tmp/pgtable';
OIDs are stored as 4-byte integers, and will overflow at 4 billion. No
one has reported this ever happening, and we plan to have the limit
removed before anyone does.
TIDs are used to identify specific physical rows with block and offset
values. TIDs change after rows are modified or reloaded. They are used
by index entries to point to physical rows.
4.17) What is the meaning of some of the terms used in PostgreSQL?
Some of the source code and older documentation use terms that have more
common usage. Here are some:
* table, relation, class
* row, record, tuple
* column, field, attribute
* retrieve, select
* replace, update
* append, insert
* OID, serial value
* portal, cursor
* range variable, table name, table alias
A list of general database terms can be found at:
http://hea-www.harvard.edu/MST/simul/software/docs/pkgs/pgsql/glossary/glossary.html
4.18) Why do I get the error /"ERROR: Memory exhausted in
AllocSetAlloc()"/?
You probably have run out of virtual memory on your system, or your
kernel has a low limit for certain resources. Try this before starting
/postmaster/:
ulimit -d 262144
limit datasize 256m
Depending on your shell, only one of these may succeed, but it will set
your process data segment limit much higher and perhaps allow the query
to complete. This command applies to the current process, and all
subprocesses created after the command is run. If you are having a
problem with the SQL client because the backend is returning too much
data, try it before starting the client.
4.19) How do I tell what PostgreSQL version I am running?
From /psql/, type |SELECT version();|
4.20) Why does my large-object operations get /"invalid large
obj descriptor"/?
You need to put |BEGIN WORK| and |COMMIT| around any use of a large
object handle, that is, surrounding |lo_open| ... |lo_close.|
Currently PostgreSQL enforces the rule by closing large object handles
at transaction commit. So the first attempt to do anything with the
handle will draw /invalid large obj descriptor/. So code that used to
work (at least most of the time) will now generate that error message if
you fail to use a transaction.
If you are using a client interface like ODBC you may need to set
|auto-commit off.|
4.21) How do I create a column that will default to the current
time?
Use /CURRENT_TIMESTAMP/:
|CREATE TABLE test (x int, modtime timestamp DEFAULT CURRENT_TIMESTAMP );
|
4.22) Why are my subqueries using |IN| so slow?
Currently, we join subqueries to outer queries by sequentially scanning
the result of the subquery for each row of the outer query. If the
subquery returns only a few rows and the outer query returns many rows,
|IN| is fastest. To speed up other queries, replace |IN| with |EXISTS|:
SELECT *
FROM tab
WHERE col IN (SELECT subcol FROM subtab);
to:
SELECT *
FROM tab
WHERE EXISTS (SELECT subcol FROM subtab WHERE subcol = col);
For this to be fast, |subcol| should be an indexed column. This
preformance problem will be fixed in 7.4.
4.23) How do I perform an outer join?
PostgreSQL supports outer joins using the SQL standard syntax. Here are
two examples:
SELECT *
FROM t1 LEFT OUTER JOIN t2 ON (t1.col = t2.col);
or
SELECT *
FROM t1 LEFT OUTER JOIN t2 USING (col);
These identical queries join t1.col to t2.col, and also return any
unjoined rows in t1 (those with no match in t2). A RIGHT join would add
unjoined rows of t2. A FULL join would return the matched rows plus all
unjoined rows from t1 and t2. The word OUTER is optional and is assumed
in LEFT, RIGHT, and FULL joins. Ordinary joins are called INNER joins.
In previous releases, outer joins can be simulated using UNION and NOT
IN. For example, when joining /tab1/ and /tab2/, the following query
does an /outer/ join of the two tables:
SELECT tab1.col1, tab2.col2
FROM tab1, tab2
WHERE tab1.col1 = tab2.col1
UNION ALL
SELECT tab1.col1, NULL
FROM tab1
WHERE tab1.col1 NOT IN (SELECT tab2.col1 FROM tab2)
ORDER BY col1
4.24) How do I perform queries using multiple databases?
There is no way to query a database other than the current one. Because
PostgreSQL loads database-specific system catalogs, it is uncertain how
a cross-database query should even behave.
/contrib/dblink/ allows cross-database queries using function calls. Of
course, a client can make simultaneous connections to different
databases and merge the results on the client side.
4.25) How do I return multiple rows or columns from a function?
In 7.3, you can easily return multiple rows or columns from a function,
http://techdocs.postgresql.org/guides/SetReturningFunctions
<http://techdocs.postgresql.org/guides/SetReturningFunctions>.
4.26) Why can't I reliably create/drop temporary tables in
PL/PgSQL functions?
PL/PgSQL caches function contents, and an unfortunate side effect is
that if a PL/PgSQL function accesses a temporary table, and that table
is later dropped and recreated, and the function called again, the
function will fail because the cached function contents still point to
the old temporary table. The solution is to use EXECUTE for temporary
table access in PL/PgSQL. This will cause the query to be reparsed every
time.
4.27) What replication options are available?
There are several master/slave replication options available. These
allow only the master to make database changes and the slave can only do
database reads. The bottom of
http://gborg.PostgreSQL.org/genpage?replication_research
<http://gborg.postgresql.org/genpage?replication_research> lists them. A
multi-master replication solution is being worked on at
http://gborg.PostgreSQL.org/project/pgreplication/projdisplay.php
<http://gborg.postgresql.org/project/pgreplication/projdisplay.php>.
4.28) What encryption options are available?
* /contrib/pgcrypto/ contains many encryption functions for use in
SQL queries.
* The only way to encrypt transmission from the client to the server
is by using /hostssl/ in /pg_hba.conf/.
* Database user passwords are automatically encrypted when stored in
version 7.3. In previous versions, you must enable the option
/PASSWORD_ENCRYPTION/ in /postgresql.conf/.
* The server can run using an encrypted file system.
------------------------------------------------------------------------
Extending PostgreSQL
5.1) I wrote a user-defined function. When I run it in /psql/,
why does it dump core?
The problem could be a number of things. Try testing your user-defined
function in a stand-alone test program first.
5.2) How can I contribute some nifty new types and functions to
PostgreSQL?
Send your extensions to the /pgsql-hackers/ mailing list, and they will
eventually end up in the /contrib// subdirectory.
5.3) Bir tuple d<>nd<6E>rmek i<>in bir C fonksiyonunu nas<61>l yazar<61>m?
PostgreSQL 7.3 s<>r<EFBFBD>m<EFBFBD> ile birlikte, C, PL/PgSQL ve SQL kullan<61>larak
tablo-d<>nd<6E>ren fonksiyonlar tamamen desteklenmektedir. Ayr<79>nt<6E>l<EFBFBD> bilgi
i<EFBFBD>in "Programmer's Guide" a bakabilrisiniz. Bir <20>rne<6E>i
/contrib/tablefunc/ i<>inde bulabilirsiniz.
5.4) Bir kaynak dosyas<61>nda de<64>i<EFBFBD>iklik yapt<70>m. Yeniden derlememe
ra<72>men de<64>i<EFBFBD>iklik ge<67>erli olmuyor. Neden?
/Makefile'lar/ include dosyalar<61> i<>in tam bir ba<62><61>ml<6D>l<EFBFBD>k i<>ermezler.
<EFBFBD>ncelikle /make clean/, ard<72>ndan da baska bir /make/ i<>lemi yapman<61>z
gerekir. GCC kullan<61>yorsaniz, /configure/ beti<74>inin /--enable-depend/
se<EFBFBD>ene<EFBFBD>ini, derleyicinin ba<62><61>ml<6D>l<EFBFBD>klar<61> otomatik olarak hesaplamas<61> i<>in
kullanabilirsiniz.
Reference in New Issue Copy Permalink