84c18acaf6
The parallel query infrastructure copies the leader backend's active snapshot to the worker processes. But BitmapHeapScan node also had bespoken code to pass the snapshot from leader to the worker. That was redundant, so remove it. The removed code was analogous to the snapshot serialization in table_parallelscan_initialize(), but that was the wrong role model. A parallel bitmap heap scan is more like an independent non-parallel bitmap heap scan in each parallel worker as far as the table AM is concerned, because the coordination is done in nodeBitmapHeapscan.c, and the table AM doesn't need to know anything about it. This relies on the assumption that es_snapshot == GetActiveSnapshot(). That's not a new assumption, things would get weird if you used the QueryDesc's snapshot for visibility checks in the scans, but the active snapshot for evaluating quals, for example. This could use some refactoring and cleanup, but for now, just add some assertions. Reviewed-by: Dilip Kumar, Robert Haas Discussion: https://www.postgresql.org/message-id/5f3b9d59-0f43-419d-80ca-6d04c07cf61a@iki.fi
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at:
https://www.postgresql.org/docs/devel/
In particular, information about building PostgreSQL from the source
code can be found at:
https://www.postgresql.org/docs/devel/installation.html
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.