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Fix ANALYZE's ancient deficiency of not trying to collect stats for expression

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indexes when the index column type (the opclass opckeytype) is different from
the expression's datatype.  When coded, this limitation wasn't worth worrying
about because we had no intelligence to speak of in stats collection for the
datatypes used by such opclasses.  However, now that there's non-toy
estimation capability for tsvector queries, it amounts to a bug that ANALYZE
fails to do this.

The fix changes struct VacAttrStats, and therefore constitutes an API break
for custom typanalyze functions.  Therefore we can't back-patch it into
released branches, but it was agreed that 9.0 isn't yet frozen hard enough
to make such a change unacceptable.  Ergo, back-patch to 9.0 but no further.
The API break had better be mentioned in 9.0 release notes.
This commit is contained in:
Tom Lane
2010-08-01 22:38:11 +00:00
parent 97532f7c29
commit 67becf8d41
2 changed files with 63 additions and 44 deletions
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19
src/include/commands/vacuum.h
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@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/commands/vacuum.h,v 1.89 2010/02/09 21:43:30 tgl Exp $
* $PostgreSQL: pgsql/src/include/commands/vacuum.h,v 1.90 2010/08/01 22:38:11 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -62,9 +62,17 @@ typedef struct VacAttrStats
/*
* These fields are set up by the main ANALYZE code before invoking the
* type-specific typanalyze function.
*
* Note: do not assume that the data being analyzed has the same datatype
* shown in attr, ie do not trust attr->atttypid, attlen, etc. This is
* because some index opclasses store a different type than the underlying
* column/expression. Instead use attrtypid, attrtypmod, and attrtype for
* information about the datatype being fed to the typanalyze function.
*/
Form_pg_attribute attr; /* copy of pg_attribute row for column */
Form_pg_type attrtype; /* copy of pg_type row for column */
Oid attrtypid; /* type of data being analyzed */
int32 attrtypmod; /* typmod of data being analyzed */
Form_pg_type attrtype; /* copy of pg_type row for attrtypid */
MemoryContext anl_context; /* where to save long-lived data */
/*
@@ -95,10 +103,9 @@ typedef struct VacAttrStats
/*
* These fields describe the stavalues[n] element types. They will be
* initialized to be the same as the column's that's underlying the slot,
* but a custom typanalyze function might want to store an array of
* something other than the analyzed column's elements. It should then
* overwrite these fields.
* initialized to match attrtypid, but a custom typanalyze function might
* want to store an array of something other than the analyzed column's
* elements. It should then overwrite these fields.
*/
Oid statypid[STATISTIC_NUM_SLOTS];
int2 statyplen[STATISTIC_NUM_SLOTS];