-$PostgreSQL: pgsql/src/backend/optimizer/README,v 1.44 2008/04/09 00:55:30 momjian Exp $
+$PostgreSQL: pgsql/src/backend/optimizer/README,v 1.45 2008/04/09 00:59:24 momjian Exp $
Optimizer
=========
1) Take each base relation in the query, and make a RelOptInfo structure
for it. Find each potentially useful way of accessing the relation,
-including sequential and index scans, and make Paths representing those
-ways. All the Paths made for a given relation are placed in its
+including sequential and index scans, and make a Path representing that
+way. All the Paths made for a given relation are placed in its
RelOptInfo.pathlist. (Actually, we discard Paths that are obviously
inferior alternatives before they ever get into the pathlist --- what
ends up in the pathlist is the cheapest way of generating each potentially
planner()
set up for recursive handling of subqueries
- do final cleanup after planning
+ do final cleanup after planning.
-subquery_planner()
pull up subqueries from rangetable, if possible
canonicalize qual
-$PostgreSQL: pgsql/src/backend/parser/README,v 1.8 2008/04/09 00:55:30 momjian Exp $
+$PostgreSQL: pgsql/src/backend/parser/README,v 1.9 2008/04/09 00:59:24 momjian Exp $
Parser
======
gram.y parse the tokens and fill query-type-specific structures
analyze.c top level of parse analysis for optimizable queries
parse_clause.c handle clauses like WHERE, ORDER BY, GROUP BY, ...
-parse_coerce.c handle coercing expressions to different data types
+parse_coerce.c handle coercing expressions to different types
parse_expr.c handle expressions like col, col + 3, x = 3 or x = 4
parse_oper.c handle operators in expressions
parse_agg.c handle aggregates, like SUM(col1), AVG(col2), ...
parse_node.c create nodes for various structures
parse_target.c handle the result list of the query
parse_relation.c support routines for tables and column handling
-parse_type.c support routines for data type handling
+parse_type.c support routines for type handling
parse_utilcmd.c parse analysis for utility commands (done at execution time)
-$PostgreSQL: pgsql/src/backend/utils/mmgr/README,v 1.13 2008/04/09 00:55:30 momjian Exp $
+$PostgreSQL: pgsql/src/backend/utils/mmgr/README,v 1.14 2008/04/09 00:59:24 momjian Exp $
Notes About Memory Allocation Redesign
======================================
Up through version 7.0, Postgres had serious problems with memory leakage
during large queries that process a lot of pass-by-reference data. There
-was no provision for recycling memory until end of query. This needed to be
-fixed, even more so with the advent of TOAST which will allowed very large
+was no provision for recycling memory until end of query. This needs to be
+fixed, even more so with the advent of TOAST which will allow very large
chunks of data to be passed around in the system. This document describes
-the new memory management system implemented in 7.1.
+the new memory management plan implemented in 7.1.
Background