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Take pg_attribute out of VacAttrStats

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The VacAttrStats structure contained the whole Form_pg_attribute for a
column, but it actually only needs attstattarget from there.  So
remove the Form_pg_attribute field and make a separate field for
attstattarget.  This simplifies some code for extended statistics that
doesn't deal with a column but an expression, which had to fake up
pg_attribute rows to satisfy internal APIs.  Also, we can remove some
comments that essentially said "don't look at pg_attribute directly".

Reviewed-by: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://www.postgresql.org/message-id/flat/d6069765-5971-04d3-c10d-e4f7b2e9c459%40eisentraut.org
This commit is contained in:
Peter Eisentraut
2023-07-03 07:09:22 +02:00
parent 7a7f60aef8
commit c69bdf837f
6 changed files with 43 additions and 80 deletions
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48
src/backend/statistics/extended_stats.c
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@@ -366,8 +366,8 @@ statext_compute_stattarget(int stattarget, int nattrs, VacAttrStats **stats)
for (i = 0; i < nattrs; i++)
{
/* keep the maximum statistics target */
if (stats[i]->attr->attstattarget > stattarget)
stattarget = stats[i]->attr->attstattarget;
if (stats[i]->attstattarget > stattarget)
stattarget = stats[i]->attstattarget;
}
/*
@@ -534,14 +534,10 @@ examine_attribute(Node *expr)
bool ok;
/*
* Create the VacAttrStats struct. Note that we only have a copy of the
* fixed fields of the pg_attribute tuple.
* Create the VacAttrStats struct.
*/
stats = (VacAttrStats *) palloc0(sizeof(VacAttrStats));
/* fake the attribute */
stats->attr = (Form_pg_attribute) palloc0(ATTRIBUTE_FIXED_PART_SIZE);
stats->attr->attstattarget = -1;
stats->attstattarget = -1;
/*
* When analyzing an expression, believe the expression tree's type not
@@ -595,7 +591,6 @@ examine_attribute(Node *expr)
if (!ok || stats->compute_stats == NULL || stats->minrows <= 0)
{
heap_freetuple(typtuple);
pfree(stats->attr);
pfree(stats);
return NULL;
}
@@ -624,6 +619,13 @@ examine_expression(Node *expr, int stattarget)
*/
stats = (VacAttrStats *) palloc0(sizeof(VacAttrStats));
/*
* We can't have statistics target specified for the expression, so we
* could use either the default_statistics_target, or the target computed
* for the extended statistics. The second option seems more reasonable.
*/
stats->attstattarget = stattarget;
/*
* When analyzing an expression, believe the expression tree's type.
*/
@@ -638,25 +640,6 @@ examine_expression(Node *expr, int stattarget)
*/
stats->attrcollid = exprCollation(expr);
/*
* We don't have any pg_attribute for expressions, so let's fake something
* reasonable into attstattarget, which is the only thing std_typanalyze
* needs.
*/
stats->attr = (Form_pg_attribute) palloc(ATTRIBUTE_FIXED_PART_SIZE);
/*
* We can't have statistics target specified for the expression, so we
* could use either the default_statistics_target, or the target computed
* for the extended statistics. The second option seems more reasonable.
*/
stats->attr->attstattarget = stattarget;
/* initialize some basic fields */
stats->attr->attrelid = InvalidOid;
stats->attr->attnum = InvalidAttrNumber;
stats->attr->atttypid = stats->attrtypid;
typtuple = SearchSysCacheCopy1(TYPEOID,
ObjectIdGetDatum(stats->attrtypid));
if (!HeapTupleIsValid(typtuple))
@@ -747,12 +730,6 @@ lookup_var_attr_stats(Relation rel, Bitmapset *attrs, List *exprs,
return NULL;
}
/*
* Sanity check that the column is not dropped - stats should have
* been removed in this case.
*/
Assert(!stats[i]->attr->attisdropped);
i++;
}
@@ -2237,8 +2214,7 @@ compute_expr_stats(Relation onerel, double totalrows,
if (tcnt > 0)
{
AttributeOpts *aopt =
get_attribute_options(stats->attr->attrelid,
stats->attr->attnum);
get_attribute_options(onerel->rd_id, stats->tupattnum);
stats->exprvals = exprvals;
stats->exprnulls = exprnulls;