bedb78d386
to eliminate unnecessary deadlocks. This commit adds SELECT ... FOR SHARE paralleling SELECT ... FOR UPDATE. The implementation uses a new SLRU data structure (managed much like pg_subtrans) to represent multiple- transaction-ID sets. When more than one transaction is holding a shared lock on a particular row, we create a MultiXactId representing that set of transactions and store its ID in the row's XMAX. This scheme allows an effectively unlimited number of row locks, just as we did before, while not costing any extra overhead except when a shared lock actually has to be shared. Still TODO: use the regular lock manager to control the grant order when multiple backends are waiting for a row lock. Alvaro Herrera and Tom Lane.
81 lines
3.2 KiB
C
81 lines
3.2 KiB
C
/*-------------------------------------------------------------------------
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*
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* parse_node.h
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* Internal definitions for parser
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*
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*
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* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/parser/parse_node.h,v 1.43 2005/04/28 21:47:18 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PARSE_NODE_H
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#define PARSE_NODE_H
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#include "nodes/parsenodes.h"
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#include "utils/rel.h"
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/*
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* State information used during parse analysis
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*
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* p_rtable: list of RTEs that will become the rangetable of the query.
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* Note that neither relname nor refname of these entries are necessarily
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* unique; searching the rtable by name is a bad idea.
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*
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* p_joinlist: list of join items (RangeTblRef and JoinExpr nodes) that
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* will become the fromlist of the query's top-level FromExpr node.
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*
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* p_namespace: list of join items that represents the current namespace
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* for table and column lookup. This may be just a subset of the rtable +
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* joinlist, and/or may contain entries that are not yet added to the main
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* joinlist. Note that an RTE that is present in p_namespace, but does not
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* have its inFromCl flag set, is accessible only with an explicit qualifier;
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* lookups of unqualified column names should ignore it.
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*
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* p_paramtypes: an array of p_numparams type OIDs for $n parameter symbols
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* (zeroth entry in array corresponds to $1). If p_variableparams is true, the
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* set of param types is not predetermined; in that case, a zero array entry
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* means that parameter number hasn't been seen, and UNKNOWNOID means the
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* parameter has been used but its type is not yet known. NOTE: in a stack
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* of ParseStates, only the topmost ParseState contains paramtype info; but
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* we copy the p_variableparams flag down to the child nodes for speed in
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* coerce_type.
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*/
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typedef struct ParseState
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{
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struct ParseState *parentParseState; /* stack link */
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List *p_rtable; /* range table so far */
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List *p_joinlist; /* join items so far (will become FromExpr
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* node's fromlist) */
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List *p_namespace; /* current lookup namespace (join items) */
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Oid *p_paramtypes; /* OIDs of types for $n parameter symbols */
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int p_numparams; /* allocated size of p_paramtypes[] */
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int p_next_resno; /* next targetlist resno to assign */
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List *p_lockedRels; /* FOR UPDATE/SHARE, if any (see gram.y) */
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Node *p_value_substitute; /* what to replace VALUE with, if
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* any */
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bool p_variableparams;
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bool p_hasAggs;
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bool p_hasSubLinks;
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bool p_is_insert;
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bool p_is_update;
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Relation p_target_relation;
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RangeTblEntry *p_target_rangetblentry;
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} ParseState;
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extern ParseState *make_parsestate(ParseState *parentParseState);
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extern Var *make_var(ParseState *pstate, RangeTblEntry *rte, int attrno);
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extern Oid transformArrayType(Oid arrayType);
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extern ArrayRef *transformArraySubscripts(ParseState *pstate,
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Node *arrayBase,
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Oid arrayType,
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Oid elementType,
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int32 elementTypMod,
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List *indirection,
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Node *assignFrom);
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extern Const *make_const(Value *value);
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#endif /* PARSE_NODE_H */
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