1 files changed, 296 insertions, 0 deletions
diff --git a/src/backend/commands/statscmds.c b/src/backend/commands/statscmds.c
new file mode 100644
index 00000000000..416309106a7
--- /dev/null
+++ b/src/backend/commands/statscmds.c
@@ -0,0 +1,296 @@
+/*-------------------------------------------------------------------------
+ *
+ * statscmds.c
+ *	  Commands for creating and altering extended statistics
+ *
+ * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/commands/statscmds.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/relscan.h"
+#include "catalog/dependency.h"
+#include "catalog/indexing.h"
+#include "catalog/namespace.h"
+#include "catalog/pg_namespace.h"
+#include "catalog/pg_statistic_ext.h"
+#include "commands/defrem.h"
+#include "miscadmin.h"
+#include "statistics/statistics.h"
+#include "utils/builtins.h"
+#include "utils/inval.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "utils/syscache.h"
+#include "utils/typcache.h"
+
+
+/* used for sorting the attnums in CreateStatistics */
+static int
+compare_int16(const void *a, const void *b)
+{
+	return memcmp(a, b, sizeof(int16));
+}
+
+/*
+ *		CREATE STATISTICS
+ */
+ObjectAddress
+CreateStatistics(CreateStatsStmt *stmt)
+{
+	int			i;
+	ListCell   *l;
+	int16		attnums[STATS_MAX_DIMENSIONS];
+	int			numcols = 0;
+	ObjectAddress address = InvalidObjectAddress;
+	char	   *namestr;
+	NameData	staname;
+	Oid			statoid;
+	Oid			namespaceId;
+	HeapTuple	htup;
+	Datum		values[Natts_pg_statistic_ext];
+	bool		nulls[Natts_pg_statistic_ext];
+	int2vector *stakeys;
+	Relation	statrel;
+	Relation	rel;
+	Oid			relid;
+	ObjectAddress parentobject,
+				childobject;
+	Datum		types[1];		/* only ndistinct defined now */
+	int			ntypes;
+	ArrayType  *staenabled;
+	bool		build_ndistinct;
+	bool		requested_type = false;
+
+	Assert(IsA(stmt, CreateStatsStmt));
+
+	/* resolve the pieces of the name (namespace etc.) */
+	namespaceId = QualifiedNameGetCreationNamespace(stmt->defnames, &namestr);
+	namestrcpy(&staname, namestr);
+
+	/*
+	 * If if_not_exists was given and the statistics already exists, bail out.
+	 */
+	if (SearchSysCacheExists2(STATEXTNAMENSP,
+							  PointerGetDatum(&staname),
+							  ObjectIdGetDatum(namespaceId)))
+	{
+		if (stmt->if_not_exists)
+		{
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_OBJECT),
+					 errmsg("statistics \"%s\" already exist, skipping",
+							namestr)));
+			return InvalidObjectAddress;
+		}
+
+		ereport(ERROR,
+				(errcode(ERRCODE_DUPLICATE_OBJECT),
+				 errmsg("statistics \"%s\" already exist", namestr)));
+	}
+
+	rel = heap_openrv(stmt->relation, AccessExclusiveLock);
+	relid = RelationGetRelid(rel);
+
+	if (rel->rd_rel->relkind != RELKIND_RELATION &&
+		rel->rd_rel->relkind != RELKIND_MATVIEW)
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("relation \"%s\" is not a table or materialized view",
+						RelationGetRelationName(rel))));
+
+	/*
+	 * Transform column names to array of attnums. While at it, enforce some
+	 * constraints.
+	 */
+	foreach(l, stmt->keys)
+	{
+		char	   *attname = strVal(lfirst(l));
+		HeapTuple	atttuple;
+		Form_pg_attribute attForm;
+		TypeCacheEntry *type;
+
+		atttuple = SearchSysCacheAttName(relid, attname);
+		if (!HeapTupleIsValid(atttuple))
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_COLUMN),
+			  errmsg("column \"%s\" referenced in statistics does not exist",
+					 attname)));
+		attForm = (Form_pg_attribute) GETSTRUCT(atttuple);
+
+		/* Disallow use of system attributes in extended stats */
+		if (attForm->attnum < 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("statistic creation on system columns is not supported")));
+
+		/* Disallow data types without a less-than operator */
+		type = lookup_type_cache(attForm->atttypid, TYPECACHE_LT_OPR);
+		if (type->lt_opr == InvalidOid)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("only scalar types can be used in extended statistics")));
+
+		/* Make sure no more than STATS_MAX_DIMENSIONS columns are used */
+		if (numcols >= STATS_MAX_DIMENSIONS)
+			ereport(ERROR,
+					(errcode(ERRCODE_TOO_MANY_COLUMNS),
+					 errmsg("cannot have more than %d keys in statistics",
+							STATS_MAX_DIMENSIONS)));
+
+		attnums[numcols] = ((Form_pg_attribute) GETSTRUCT(atttuple))->attnum;
+		ReleaseSysCache(atttuple);
+		numcols++;
+	}
+
+	/*
+	 * Check that at least two columns were specified in the statement. The
+	 * upper bound was already checked in the loop above.
+	 */
+	if (numcols < 2)
+		ereport(ERROR,
+				(errcode(ERRCODE_TOO_MANY_COLUMNS),
+				 errmsg("statistics require at least 2 columns")));
+
+	/*
+	 * Sort the attnums, which makes detecting duplicies somewhat easier, and
+	 * it does not hurt (it does not affect the efficiency, unlike for
+	 * indexes, for example).
+	 */
+	qsort(attnums, numcols, sizeof(int16), compare_int16);
+
+	/*
+	 * Look for duplicities in the list of columns. The attnums are sorted so
+	 * just check consecutive elements.
+	 */
+	for (i = 1; i < numcols; i++)
+		if (attnums[i] == attnums[i - 1])
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_COLUMN),
+				  errmsg("duplicate column name in statistics definition")));
+
+	stakeys = buildint2vector(attnums, numcols);
+
+	/*
+	 * Parse the statistics options.  Currently only statistics types are
+	 * recognized.
+	 */
+	build_ndistinct = false;
+	foreach(l, stmt->options)
+	{
+		DefElem    *opt = (DefElem *) lfirst(l);
+
+		if (strcmp(opt->defname, "ndistinct") == 0)
+		{
+			build_ndistinct = defGetBoolean(opt);
+			requested_type = true;
+		}
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("unrecognized STATISTICS option \"%s\"",
+							opt->defname)));
+	}
+	/* If no statistic type was specified, build them all. */
+	if (!requested_type)
+		build_ndistinct = true;
+
+	/* construct the char array of enabled statistic types */
+	ntypes = 0;
+	if (build_ndistinct)
+		types[ntypes++] = CharGetDatum(STATS_EXT_NDISTINCT);
+	Assert(ntypes > 0);
+	staenabled = construct_array(types, ntypes, CHAROID, 1, true, 'c');
+
+	/*
+	 * Everything seems fine, so let's build the pg_statistic_ext tuple.
+	 */
+	memset(values, 0, sizeof(values));
+	memset(nulls, false, sizeof(nulls));
+	values[Anum_pg_statistic_ext_starelid - 1] = ObjectIdGetDatum(relid);
+	values[Anum_pg_statistic_ext_staname - 1] = NameGetDatum(&staname);
+	values[Anum_pg_statistic_ext_stanamespace - 1] = ObjectIdGetDatum(namespaceId);
+	values[Anum_pg_statistic_ext_staowner - 1] = ObjectIdGetDatum(GetUserId());
+	values[Anum_pg_statistic_ext_stakeys - 1] = PointerGetDatum(stakeys);
+	values[Anum_pg_statistic_ext_staenabled - 1] = PointerGetDatum(staenabled);
+
+	/* no statistics build yet */
+	nulls[Anum_pg_statistic_ext_standistinct - 1] = true;
+
+	/* insert it into pg_statistic_ext */
+	statrel = heap_open(StatisticExtRelationId, RowExclusiveLock);
+	htup = heap_form_tuple(statrel->rd_att, values, nulls);
+	CatalogTupleInsert(statrel, htup);
+	statoid = HeapTupleGetOid(htup);
+	heap_freetuple(htup);
+	heap_close(statrel, RowExclusiveLock);
+	relation_close(rel, NoLock);
+
+	/*
+	 * Add a dependency on a table, so that stats get dropped on DROP TABLE.
+	 */
+	ObjectAddressSet(parentobject, RelationRelationId, relid);
+	ObjectAddressSet(childobject, StatisticExtRelationId, statoid);
+	recordDependencyOn(&childobject, &parentobject, DEPENDENCY_AUTO);
+
+	/*
+	 * Also add dependency on the schema.  This is required to ensure that we
+	 * drop the statistics on DROP SCHEMA.  This is not handled automatically
+	 * by DROP TABLE because the statistics are not an object in the table's
+	 * schema.
+	 */
+	ObjectAddressSet(parentobject, NamespaceRelationId, namespaceId);
+	recordDependencyOn(&childobject, &parentobject, DEPENDENCY_AUTO);
+
+	ObjectAddressSet(address, StatisticExtRelationId, statoid);
+
+	/*
+	 * Invalidate relcache so that others see the new statistics.
+	 */
+	CacheInvalidateRelcache(rel);
+
+	return address;
+}
+
+/*
+ * Guts of statistics deletion.
+ */
+void
+RemoveStatisticsById(Oid statsOid)
+{
+	Relation	relation;
+	Oid			relid;
+	Relation	rel;
+	HeapTuple	tup;
+	Form_pg_statistic_ext statext;
+
+	/*
+	 * Delete the pg_statistic_ext tuple.
+	 */
+	relation = heap_open(StatisticExtRelationId, RowExclusiveLock);
+
+	tup = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(statsOid));
+
+	if (!HeapTupleIsValid(tup)) /* should not happen */
+		elog(ERROR, "cache lookup failed for statistics %u", statsOid);
+
+	statext = (Form_pg_statistic_ext) GETSTRUCT(tup);
+	relid = statext->starelid;
+
+	rel = heap_open(relid, AccessExclusiveLock);
+
+	simple_heap_delete(relation, &tup->t_self);
+
+	CacheInvalidateRelcache(rel);
+
+	ReleaseSysCache(tup);
+
+	heap_close(relation, RowExclusiveLock);
+	heap_close(rel, NoLock);
+}