de380a62b5
Move all responsibility for indicating a block is exhuasted into table_scan_bitmap_next_tuple() and advance the main iterator in heap-specific code. This flow control makes more sense and is a step toward using the read stream API for bitmap heap scans. Previously, table_scan_bitmap_next_block() returned false to indicate table_scan_bitmap_next_tuple() should not be called for the tuples on the page. This happened both when 1) there were no visible tuples on the page and 2) when the block returned by the iterator was past the end of the table. BitmapHeapNext() (generic bitmap table scan code) handled the case when the bitmap was exhausted. It makes more sense for table_scan_bitmap_next_tuple() to return false when there are no visible tuples on the page and table_scan_bitmap_next_block() to return false when the bitmap is exhausted or there are no more blocks in the table. As part of this new design, TBMIterateResults are no longer used as a flow control mechanism in BitmapHeapNext(), so we removed table_scan_bitmap_next_tuple's TBMIterateResult parameter. Note that the prefetch iterator is still saved in the BitmapHeapScanState node and advanced in generic bitmap table scan code. This is because 1) it was not necessary to change the prefetch iterator location to change the flow control in BitmapHeapNext() 2) modifying prefetch iterator management requires several more steps better split over multiple commits and 3) the prefetch iterator will be removed once the read stream API is used. Author: Melanie Plageman Reviewed-by: Tomas Vondra, Andres Freund, Heikki Linnakangas, Mark Dilger Discussion: https://postgr.es/m/063e4eb4-32d9-439e-a0b1-75565a9835a8%40iki.fi |
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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/.