for the first index column?
- |
- amindexnulls
- bool
-
- Does the access method support null index entries?
-
-
|
amsearchnulls
bool
Build new index
function
+ |
+ ambuildempty
+ regproc
+ pg_proc.oid
+ Build empty index
function
+
+
|
ambulkdelete
regproc
where no indexable restriction clause is given for the first index column.
When amcanmulticol is false,
amoptionalkey essentially says whether the
- access method allows full-index scans without any restriction clause.
+ access method supports full-index scans without any restriction clause.
Access methods that support multiple index columns must
support scans that omit restrictions on any or all of the columns after
the first; however they are permitted to require some restriction to
appear for the first index column, and this is signaled by setting
amoptionalkey false.
- amindexnulls asserts that index entries are
- created for NULL key values. Since most indexable operators are
+ One reason that an index AM might set
+ amoptionalkey false is if it doesn't index
+ NULLs. Since most indexable operators are
strict and hence cannot return TRUE for NULL inputs,
it is at first sight attractive to not store index entries for null values:
they could never be returned by an index scan anyway. However, this
used to scan for rows with a = 4, which is wrong if the
index omits rows where b is null.
It is, however, OK to omit rows where the first indexed column is null.
- Thus, amindexnulls should be set true only if the
- index access method indexes all rows, including arbitrary combinations of
- null values. An index access method that sets
- amindexnulls may also set
+ An index access method that does index nulls may also set
amsearchnulls, indicating that it supports
IS NULL and IS NOT NULL clauses as search
conditions.
errmsg("cannot cluster on partial index \"%s\"",
RelationGetRelationName(OldIndex))));
- if (!OldIndex->rd_am->amindexnulls)
- {
- AttrNumber colno;
-
- /*
- * If the AM doesn't index nulls, then it's a partial index unless we
- * can prove all the rows are non-null. Note we only need look at the
- * first column; multicolumn-capable AMs are *required* to index nulls
- * in columns after the first.
- */
- colno = OldIndex->rd_index->indkey.values[0];
- if (colno > 0)
- {
- /* ordinary user attribute */
- if (!OldHeap->rd_att->attrs[colno - 1]->attnotnull)
- ereport(ERROR,
- (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
- errmsg("cannot cluster on index \"%s\" because access method does not handle null values",
- RelationGetRelationName(OldIndex)),
- recheck
- ? errhint("You might be able to work around this by marking column \"%s\" NOT NULL, or use ALTER TABLE ... SET WITHOUT CLUSTER to remove the cluster specification from the table.",
- NameStr(OldHeap->rd_att->attrs[colno - 1]->attname))
- : errhint("You might be able to work around this by marking column \"%s\" NOT NULL.",
- NameStr(OldHeap->rd_att->attrs[colno - 1]->attname))));
- }
- else if (colno < 0)
- {
- /* system column --- okay, always non-null */
- }
- else
- /* index expression, lose... */
- ereport(ERROR,
- (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
- errmsg("cannot cluster on expressional index \"%s\" because its index access method does not handle null values",
- RelationGetRelationName(OldIndex))));
- }
-
/*
* Disallow if index is left over from a failed CREATE INDEX CONCURRENTLY;
* it might well not contain entries for every heap row, or might not even
*/
/* yyyymmddN */
-#define CATALOG_VERSION_NO 201101071
+#define CATALOG_VERSION_NO 201101081
#endif
bool amcanunique; /* does AM support UNIQUE indexes? */
bool amcanmulticol; /* does AM support multi-column indexes? */
bool amoptionalkey; /* can query omit key for the first column? */
- bool amindexnulls; /* does AM support NULL index entries? */
bool amsearchnulls; /* can AM search for NULL/NOT NULL entries? */
bool amstorage; /* can storage type differ from column type? */
bool amclusterable; /* does AM support cluster command? */
#define Anum_pg_am_amcanunique 7
#define Anum_pg_am_amcanmulticol 8
#define Anum_pg_am_amoptionalkey 9
-#define Anum_pg_am_amindexnulls 10
-#define Anum_pg_am_amsearchnulls 11
-#define Anum_pg_am_amstorage 12
-#define Anum_pg_am_amclusterable 13
-#define Anum_pg_am_amkeytype 14
-#define Anum_pg_am_aminsert 15
-#define Anum_pg_am_ambeginscan 16
-#define Anum_pg_am_amgettuple 17
-#define Anum_pg_am_amgetbitmap 18
-#define Anum_pg_am_amrescan 19
-#define Anum_pg_am_amendscan 20
-#define Anum_pg_am_ammarkpos 21
-#define Anum_pg_am_amrestrpos 22
-#define Anum_pg_am_ambuild 23
-#define Anum_pg_am_ambuildempty 24
-#define Anum_pg_am_ambulkdelete 25
-#define Anum_pg_am_amvacuumcleanup 26
-#define Anum_pg_am_amcostestimate 27
-#define Anum_pg_am_amoptions 28
+#define Anum_pg_am_amsearchnulls 10
+#define Anum_pg_am_amstorage 11
+#define Anum_pg_am_amclusterable 12
+#define Anum_pg_am_amkeytype 13
+#define Anum_pg_am_aminsert 14
+#define Anum_pg_am_ambeginscan 15
+#define Anum_pg_am_amgettuple 16
+#define Anum_pg_am_amgetbitmap 17
+#define Anum_pg_am_amrescan 18
+#define Anum_pg_am_amendscan 19
+#define Anum_pg_am_ammarkpos 20
+#define Anum_pg_am_amrestrpos 21
+#define Anum_pg_am_ambuild 22
+#define Anum_pg_am_ambuildempty 23
+#define Anum_pg_am_ambulkdelete 24
+#define Anum_pg_am_amvacuumcleanup 25
+#define Anum_pg_am_amcostestimate 26
+#define Anum_pg_am_amoptions 27
/* ----------------
* initial contents of pg_am
* ----------------
*/
-DATA(insert OID = 403 ( btree 5 1 t f t t t t t t f t 0 btinsert btbeginscan btgettuple btgetbitmap btrescan btendscan btmarkpos btrestrpos btbuild btbuildempty btbulkdelete btvacuumcleanup btcostestimate btoptions ));
+DATA(insert OID = 403 ( btree 5 1 t f t t t t t f t 0 btinsert btbeginscan btgettuple btgetbitmap btrescan btendscan btmarkpos btrestrpos btbuild btbuildempty btbulkdelete btvacuumcleanup btcostestimate btoptions ));
DESCR("b-tree index access method");
#define BTREE_AM_OID 403
-DATA(insert OID = 405 ( hash 1 1 f f t f f f f f f f 23 hashinsert hashbeginscan hashgettuple hashgetbitmap hashrescan hashendscan hashmarkpos hashrestrpos hashbuild hashbuildempty hashbulkdelete hashvacuumcleanup hashcostestimate hashoptions ));
+DATA(insert OID = 405 ( hash 1 1 f f t f f f f f f 23 hashinsert hashbeginscan hashgettuple hashgetbitmap hashrescan hashendscan hashmarkpos hashrestrpos hashbuild hashbuildempty hashbulkdelete hashvacuumcleanup hashcostestimate hashoptions ));
DESCR("hash index access method");
#define HASH_AM_OID 405
-DATA(insert OID = 783 ( gist 0 8 f t f f t t t t t t 0 gistinsert gistbeginscan gistgettuple gistgetbitmap gistrescan gistendscan gistmarkpos gistrestrpos gistbuild gistbuildempty gistbulkdelete gistvacuumcleanup gistcostestimate gistoptions ));
+DATA(insert OID = 783 ( gist 0 8 f t f f t t t t t 0 gistinsert gistbeginscan gistgettuple gistgetbitmap gistrescan gistendscan gistmarkpos gistrestrpos gistbuild gistbuildempty gistbulkdelete gistvacuumcleanup gistcostestimate gistoptions ));
DESCR("GiST index access method");
#define GIST_AM_OID 783
-DATA(insert OID = 2742 ( gin 0 5 f f f f t t f f t f 0 gininsert ginbeginscan - gingetbitmap ginrescan ginendscan ginmarkpos ginrestrpos ginbuild ginbuildempty ginbulkdelete ginvacuumcleanup gincostestimate ginoptions ));
+DATA(insert OID = 2742 ( gin 0 5 f f f f t t f t f 0 gininsert ginbeginscan - gingetbitmap ginrescan ginendscan ginmarkpos ginrestrpos ginbuild ginbuildempty ginbulkdelete ginvacuumcleanup gincostestimate ginoptions ));
DESCR("GIN index access method");
#define GIN_AM_OID 2742
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