-<!-- $PostgreSQL: pgsql/doc/src/sgml/queries.sgml,v 1.58 2010/07/03 02:57:46 rhaas Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/queries.sgml,v 1.59 2010/08/07 02:44:05 tgl Exp $ -->
<chapter id="queries">
<title>Queries</title>
In this example, the columns <literal>product_id</literal>,
<literal>p.name</literal>, and <literal>p.price</literal> must be
in the <literal>GROUP BY</> clause since they are referenced in
- the query select list. (Depending on how the products
- table is set up, name and price might be fully dependent on the
- product ID, so the additional groupings could theoretically be
- unnecessary, though this is not implemented.) The column
+ the query select list (but see below). The column
<literal>s.units</> does not have to be in the <literal>GROUP
BY</> list since it is only used in an aggregate expression
(<literal>sum(...)</literal>), which represents the sales
all sales of the product.
</para>
+ <para>
+ If the products table is set up so that,
+ say, <literal>product_id</literal> is the primary key, then it
+ would be enough to group by <literal>product_id</literal> in the
+ above example, since name and price would
+ be <firstterm>functionally
+ dependent</firstterm><indexterm><primary>functional
+ dependency</primary></indexterm> on the product ID, and so there
+ would be no ambiguity about which name and price value to return
+ for each product ID group.
+ </para>
+
<para>
In strict SQL, <literal>GROUP BY</> can only group by columns of
the source table but <productname>PostgreSQL</productname> extends
<!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/select.sgml,v 1.131 2010/06/15 20:04:53 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/select.sgml,v 1.132 2010/08/07 02:44:05 tgl Exp $
PostgreSQL documentation
-->
produces a single value computed across all the selected rows).
When <literal>GROUP BY</literal> is present, it is not valid for
the <command>SELECT</command> list expressions to refer to
- ungrouped columns except within aggregate functions, since there
- would be more than one possible value to return for an ungrouped
- column.
+ ungrouped columns except within aggregate functions or if the
+ ungrouped column is functionally dependent on the grouped columns,
+ since there would otherwise be more than one possible value to
+ return for an ungrouped column. A functional dependency exists if
+ the grouped columns (or a subset thereof) are the primary key of
+ the table containing the ungrouped column.
</para>
</refsect2>
</para>
</refsect2>
+ <refsect2>
+ <title>Functional Dependencies</title>
+
+ <para>
+ <productname>PostgreSQL</productname> recognizes functional dependency
+ (allowing columns to be omitted from <literal>GROUP BY</>) only when
+ a table's primary key is included in the <literal>GROUP BY</> list.
+ The SQL standard specifies additional conditions that should be
+ recognized.
+ </para>
+ </refsect2>
+
<refsect2>
<title><literal>WINDOW</literal> Clause Restrictions</title>
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/catalog/dependency.c,v 1.96 2010/02/26 02:00:36 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/catalog/dependency.c,v 1.97 2010/08/07 02:44:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
{
/* Recurse into RTE subquery or not-yet-planned sublink subquery */
Query *query = (Query *) node;
- ListCell *rtable;
+ ListCell *lc;
bool result;
/*
* of recursing into RTE_FUNCTION RTEs, subqueries, etc, so no need to
* do that here. But keep it from looking at join alias lists.)
*/
- foreach(rtable, query->rtable)
+ foreach(lc, query->rtable)
{
- RangeTblEntry *rte = (RangeTblEntry *) lfirst(rtable);
+ RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
ListCell *ct;
switch (rte->rtekind)
}
}
+ /*
+ * Add dependencies on constraints listed in query's constraintDeps
+ */
+ foreach(lc, query->constraintDeps)
+ {
+ add_object_address(OCLASS_CONSTRAINT, lfirst_oid(lc), 0,
+ context->addrs);
+ }
+
/* query_tree_walker ignores ORDER BY etc, but we need those opers */
find_expr_references_walker((Node *) query->sortClause, context);
find_expr_references_walker((Node *) query->groupClause, context);
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/catalog/pg_constraint.c,v 1.54 2010/08/05 15:25:35 rhaas Exp $
+ * $PostgreSQL: pgsql/src/backend/catalog/pg_constraint.c,v 1.55 2010/08/07 02:44:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
return conOid;
}
+
+/*
+ * Determine whether a relation can be proven functionally dependent on
+ * a set of grouping columns. If so, return TRUE and add the pg_constraint
+ * OIDs of the constraints needed for the proof to the *constraintDeps list.
+ *
+ * grouping_columns is a list of grouping expressions, in which columns of
+ * the rel of interest are Vars with the indicated varno/varlevelsup.
+ *
+ * Currently we only check to see if the rel has a primary key that is a
+ * subset of the grouping_columns. We could also use plain unique constraints
+ * if all their columns are known not null, but there's a problem: we need
+ * to be able to represent the not-null-ness as part of the constraints added
+ * to *constraintDeps. FIXME whenever not-null constraints get represented
+ * in pg_constraint.
+ */
+bool
+check_functional_grouping(Oid relid,
+ Index varno, Index varlevelsup,
+ List *grouping_columns,
+ List **constraintDeps)
+{
+ bool result = false;
+ Relation pg_constraint;
+ HeapTuple tuple;
+ SysScanDesc scan;
+ ScanKeyData skey[1];
+
+ /* Scan pg_constraint for constraints of the target rel */
+ pg_constraint = heap_open(ConstraintRelationId, AccessShareLock);
+
+ ScanKeyInit(&skey[0],
+ Anum_pg_constraint_conrelid,
+ BTEqualStrategyNumber, F_OIDEQ,
+ ObjectIdGetDatum(relid));
+
+ scan = systable_beginscan(pg_constraint, ConstraintRelidIndexId, true,
+ SnapshotNow, 1, skey);
+
+ while (HeapTupleIsValid(tuple = systable_getnext(scan)))
+ {
+ Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tuple);
+ Datum adatum;
+ bool isNull;
+ ArrayType *arr;
+ int16 *attnums;
+ int numkeys;
+ int i;
+ bool found_col;
+
+ /* Only PK constraints are of interest for now, see comment above */
+ if (con->contype != CONSTRAINT_PRIMARY)
+ continue;
+
+ /* Extract the conkey array, ie, attnums of PK's columns */
+ adatum = heap_getattr(tuple, Anum_pg_constraint_conkey,
+ RelationGetDescr(pg_constraint), &isNull);
+ if (isNull)
+ elog(ERROR, "null conkey for constraint %u",
+ HeapTupleGetOid(tuple));
+ arr = DatumGetArrayTypeP(adatum); /* ensure not toasted */
+ numkeys = ARR_DIMS(arr)[0];
+ if (ARR_NDIM(arr) != 1 ||
+ numkeys < 0 ||
+ ARR_HASNULL(arr) ||
+ ARR_ELEMTYPE(arr) != INT2OID)
+ elog(ERROR, "conkey is not a 1-D smallint array");
+ attnums = (int16 *) ARR_DATA_PTR(arr);
+
+ found_col = false;
+ for (i = 0; i < numkeys; i++)
+ {
+ AttrNumber attnum = attnums[i];
+ ListCell *gl;
+
+ found_col = false;
+ foreach(gl, grouping_columns)
+ {
+ Var *gvar = (Var *) lfirst(gl);
+
+ if (IsA(gvar, Var) &&
+ gvar->varno == varno &&
+ gvar->varlevelsup == varlevelsup &&
+ gvar->varattno == attnum)
+ {
+ found_col = true;
+ break;
+ }
+ }
+ if (!found_col)
+ break;
+ }
+
+ if (found_col)
+ {
+ /* The PK is a subset of grouping_columns, so we win */
+ *constraintDeps = lappend_oid(*constraintDeps,
+ HeapTupleGetOid(tuple));
+ result = true;
+ break;
+ }
+ }
+
+ systable_endscan(scan);
+
+ heap_close(pg_constraint, AccessShareLock);
+
+ return result;
+}
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.466 2010/07/25 23:21:21 rhaas Exp $
+ * $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.467 2010/08/07 02:44:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
COPY_NODE_FIELD(limitCount);
COPY_NODE_FIELD(rowMarks);
COPY_NODE_FIELD(setOperations);
+ COPY_NODE_FIELD(constraintDeps);
return newnode;
}
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.386 2010/07/25 23:21:21 rhaas Exp $
+ * $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.387 2010/08/07 02:44:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
COMPARE_NODE_FIELD(limitCount);
COMPARE_NODE_FIELD(rowMarks);
COMPARE_NODE_FIELD(setOperations);
+ COMPARE_NODE_FIELD(constraintDeps);
return true;
}
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.387 2010/07/25 23:21:21 rhaas Exp $
+ * $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.388 2010/08/07 02:44:06 tgl Exp $
*
* NOTES
* Every node type that can appear in stored rules' parsetrees *must*
WRITE_NODE_FIELD(limitCount);
WRITE_NODE_FIELD(rowMarks);
WRITE_NODE_FIELD(setOperations);
+ WRITE_NODE_FIELD(constraintDeps);
}
static void
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.232 2010/02/16 22:34:43 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.233 2010/08/07 02:44:07 tgl Exp $
*
* NOTES
* Path and Plan nodes do not have any readfuncs support, because we
READ_NODE_FIELD(limitCount);
READ_NODE_FIELD(rowMarks);
READ_NODE_FIELD(setOperations);
+ READ_NODE_FIELD(constraintDeps);
READ_DONE();
}
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/parser/parse_agg.c,v 1.93 2010/03/17 16:52:38 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/parser/parse_agg.c,v 1.94 2010/08/07 02:44:07 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
+#include "catalog/pg_constraint.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/tlist.h"
typedef struct
{
ParseState *pstate;
+ Query *qry;
List *groupClauses;
bool have_non_var_grouping;
+ List **func_grouped_rels;
int sublevels_up;
} check_ungrouped_columns_context;
-static void check_ungrouped_columns(Node *node, ParseState *pstate,
- List *groupClauses, bool have_non_var_grouping);
+static void check_ungrouped_columns(Node *node, ParseState *pstate, Query *qry,
+ List *groupClauses, bool have_non_var_grouping,
+ List **func_grouped_rels);
static bool check_ungrouped_columns_walker(Node *node,
check_ungrouped_columns_context *context);
{
List *groupClauses = NIL;
bool have_non_var_grouping;
+ List *func_grouped_rels = NIL;
ListCell *l;
bool hasJoinRTEs;
bool hasSelfRefRTEs;
clause = (Node *) qry->targetList;
if (hasJoinRTEs)
clause = flatten_join_alias_vars(root, clause);
- check_ungrouped_columns(clause, pstate,
- groupClauses, have_non_var_grouping);
+ check_ungrouped_columns(clause, pstate, qry,
+ groupClauses, have_non_var_grouping,
+ &func_grouped_rels);
clause = (Node *) qry->havingQual;
if (hasJoinRTEs)
clause = flatten_join_alias_vars(root, clause);
- check_ungrouped_columns(clause, pstate,
- groupClauses, have_non_var_grouping);
+ check_ungrouped_columns(clause, pstate, qry,
+ groupClauses, have_non_var_grouping,
+ &func_grouped_rels);
/*
* Per spec, aggregates can't appear in a recursive term.
* way more pain than the feature seems worth.
*/
static void
-check_ungrouped_columns(Node *node, ParseState *pstate,
- List *groupClauses, bool have_non_var_grouping)
+check_ungrouped_columns(Node *node, ParseState *pstate, Query *qry,
+ List *groupClauses, bool have_non_var_grouping,
+ List **func_grouped_rels)
{
check_ungrouped_columns_context context;
context.pstate = pstate;
+ context.qry = qry;
context.groupClauses = groupClauses;
context.have_non_var_grouping = have_non_var_grouping;
+ context.func_grouped_rels = func_grouped_rels;
context.sublevels_up = 0;
check_ungrouped_columns_walker(node, &context);
}
}
}
- /* Found an ungrouped local variable; generate error message */
+ /*
+ * Check whether the Var is known functionally dependent on the GROUP
+ * BY columns. If so, we can allow the Var to be used, because the
+ * grouping is really a no-op for this table. However, this deduction
+ * depends on one or more constraints of the table, so we have to add
+ * those constraints to the query's constraintDeps list, because it's
+ * not semantically valid anymore if the constraint(s) get dropped.
+ * (Therefore, this check must be the last-ditch effort before raising
+ * error: we don't want to add dependencies unnecessarily.)
+ *
+ * Because this is a pretty expensive check, and will have the same
+ * outcome for all columns of a table, we remember which RTEs we've
+ * already proven functional dependency for in the func_grouped_rels
+ * list. This test also prevents us from adding duplicate entries
+ * to the constraintDeps list.
+ */
+ if (list_member_int(*context->func_grouped_rels, var->varno))
+ return false; /* previously proven acceptable */
+
Assert(var->varno > 0 &&
(int) var->varno <= list_length(context->pstate->p_rtable));
rte = rt_fetch(var->varno, context->pstate->p_rtable);
+ if (rte->rtekind == RTE_RELATION)
+ {
+ if (check_functional_grouping(rte->relid,
+ var->varno,
+ 0,
+ context->groupClauses,
+ &context->qry->constraintDeps))
+ {
+ *context->func_grouped_rels =
+ lappend_int(*context->func_grouped_rels, var->varno);
+ return false; /* acceptable */
+ }
+ }
+
+ /* Found an ungrouped local variable; generate error message */
attname = get_rte_attribute_name(rte, var->varattno);
if (context->sublevels_up == 0)
ereport(ERROR,
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.590 2010/08/05 18:21:17 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.591 2010/08/07 02:44:07 tgl Exp $
*
*-------------------------------------------------------------------------
*/
*/
/* yyyymmddN */
-#define CATALOG_VERSION_NO 201008052
+#define CATALOG_VERSION_NO 201008061
#endif
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/catalog/pg_constraint.h,v 1.40 2010/08/05 15:25:36 rhaas Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_constraint.h,v 1.41 2010/08/07 02:44:07 tgl Exp $
*
* NOTES
* the genbki.pl script reads this file and generates .bki
Oid newNspId, bool isType);
extern Oid get_constraint_oid(Oid relid, const char *conname, bool missing_ok);
+extern bool check_functional_grouping(Oid relid,
+ Index varno, Index varlevelsup,
+ List *grouping_columns,
+ List **constraintDeps);
+
#endif /* PG_CONSTRAINT_H */
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.433 2010/07/25 23:21:22 rhaas Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.434 2010/08/07 02:44:07 tgl Exp $
*
*-------------------------------------------------------------------------
*/
Node *setOperations; /* set-operation tree if this is top level of
* a UNION/INTERSECT/EXCEPT query */
+
+ List *constraintDeps; /* a list of pg_constraint OIDs that the query
+ * depends on to be semantically valid */
} Query;
--- /dev/null
+-- from http://www.depesz.com/index.php/2010/04/19/getting-unique-elements/
+CREATE TEMP TABLE articles (
+ id int CONSTRAINT articles_pkey PRIMARY KEY,
+ keywords text,
+ title text UNIQUE NOT NULL,
+ body text UNIQUE,
+ created date
+);
+NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "articles_pkey" for table "articles"
+NOTICE: CREATE TABLE / UNIQUE will create implicit index "articles_title_key" for table "articles"
+NOTICE: CREATE TABLE / UNIQUE will create implicit index "articles_body_key" for table "articles"
+CREATE TEMP TABLE articles_in_category (
+ article_id int,
+ category_id int,
+ changed date,
+ PRIMARY KEY (article_id, category_id)
+);
+NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "articles_in_category_pkey" for table "articles_in_category"
+-- test functional dependencies based on primary keys/unique constraints
+-- base tables
+-- group by primary key (OK)
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY id;
+ id | keywords | title | body | created
+----+----------+-------+------+---------
+(0 rows)
+
+-- group by unique not null (fail/todo)
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY title;
+ERROR: column "articles.id" must appear in the GROUP BY clause or be used in an aggregate function
+LINE 1: SELECT id, keywords, title, body, created
+ ^
+-- group by unique nullable (fail)
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY body;
+ERROR: column "articles.id" must appear in the GROUP BY clause or be used in an aggregate function
+LINE 1: SELECT id, keywords, title, body, created
+ ^
+-- group by something else (fail)
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY keywords;
+ERROR: column "articles.id" must appear in the GROUP BY clause or be used in an aggregate function
+LINE 1: SELECT id, keywords, title, body, created
+ ^
+-- multiple tables
+-- group by primary key (OK)
+SELECT a.id, a.keywords, a.title, a.body, a.created
+FROM articles AS a, articles_in_category AS aic
+WHERE a.id = aic.article_id AND aic.category_id in (14,62,70,53,138)
+GROUP BY a.id;
+ id | keywords | title | body | created
+----+----------+-------+------+---------
+(0 rows)
+
+-- group by something else (fail)
+SELECT a.id, a.keywords, a.title, a.body, a.created
+FROM articles AS a, articles_in_category AS aic
+WHERE a.id = aic.article_id AND aic.category_id in (14,62,70,53,138)
+GROUP BY aic.article_id, aic.category_id;
+ERROR: column "a.id" must appear in the GROUP BY clause or be used in an aggregate function
+LINE 1: SELECT a.id, a.keywords, a.title, a.body, a.created
+ ^
+-- JOIN syntax
+-- group by left table's primary key (OK)
+SELECT a.id, a.keywords, a.title, a.body, a.created
+FROM articles AS a JOIN articles_in_category AS aic ON a.id = aic.article_id
+WHERE aic.category_id in (14,62,70,53,138)
+GROUP BY a.id;
+ id | keywords | title | body | created
+----+----------+-------+------+---------
+(0 rows)
+
+-- group by something else (fail)
+SELECT a.id, a.keywords, a.title, a.body, a.created
+FROM articles AS a JOIN articles_in_category AS aic ON a.id = aic.article_id
+WHERE aic.category_id in (14,62,70,53,138)
+GROUP BY aic.article_id, aic.category_id;
+ERROR: column "a.id" must appear in the GROUP BY clause or be used in an aggregate function
+LINE 1: SELECT a.id, a.keywords, a.title, a.body, a.created
+ ^
+-- group by right table's (composite) primary key (OK)
+SELECT aic.changed
+FROM articles AS a JOIN articles_in_category AS aic ON a.id = aic.article_id
+WHERE aic.category_id in (14,62,70,53,138)
+GROUP BY aic.category_id, aic.article_id;
+ changed
+---------
+(0 rows)
+
+-- group by right table's partial primary key (fail)
+SELECT aic.changed
+FROM articles AS a JOIN articles_in_category AS aic ON a.id = aic.article_id
+WHERE aic.category_id in (14,62,70,53,138)
+GROUP BY aic.article_id;
+ERROR: column "aic.changed" must appear in the GROUP BY clause or be used in an aggregate function
+LINE 1: SELECT aic.changed
+ ^
+-- example from documentation
+CREATE TEMP TABLE products (product_id int, name text, price numeric);
+CREATE TEMP TABLE sales (product_id int, units int);
+-- OK
+SELECT product_id, p.name, (sum(s.units) * p.price) AS sales
+ FROM products p LEFT JOIN sales s USING (product_id)
+ GROUP BY product_id, p.name, p.price;
+ product_id | name | sales
+------------+------+-------
+(0 rows)
+
+-- fail
+SELECT product_id, p.name, (sum(s.units) * p.price) AS sales
+ FROM products p LEFT JOIN sales s USING (product_id)
+ GROUP BY product_id;
+ERROR: column "p.name" must appear in the GROUP BY clause or be used in an aggregate function
+LINE 1: SELECT product_id, p.name, (sum(s.units) * p.price) AS sales
+ ^
+ALTER TABLE products ADD PRIMARY KEY (product_id);
+NOTICE: ALTER TABLE / ADD PRIMARY KEY will create implicit index "products_pkey" for table "products"
+-- OK now
+SELECT product_id, p.name, (sum(s.units) * p.price) AS sales
+ FROM products p LEFT JOIN sales s USING (product_id)
+ GROUP BY product_id;
+ product_id | name | sales
+------------+------+-------
+(0 rows)
+
+-- Drupal example, http://drupal.org/node/555530
+CREATE TEMP TABLE node (
+ nid SERIAL,
+ vid integer NOT NULL default '0',
+ type varchar(32) NOT NULL default '',
+ title varchar(128) NOT NULL default '',
+ uid integer NOT NULL default '0',
+ status integer NOT NULL default '1',
+ created integer NOT NULL default '0',
+ -- snip
+ PRIMARY KEY (nid, vid)
+);
+NOTICE: CREATE TABLE will create implicit sequence "node_nid_seq" for serial column "node.nid"
+NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "node_pkey" for table "node"
+CREATE TEMP TABLE users (
+ uid integer NOT NULL default '0',
+ name varchar(60) NOT NULL default '',
+ pass varchar(32) NOT NULL default '',
+ -- snip
+ PRIMARY KEY (uid),
+ UNIQUE (name)
+);
+NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "users_pkey" for table "users"
+NOTICE: CREATE TABLE / UNIQUE will create implicit index "users_name_key" for table "users"
+-- OK
+SELECT u.uid, u.name FROM node n
+INNER JOIN users u ON u.uid = n.uid
+WHERE n.type = 'blog' AND n.status = 1
+GROUP BY u.uid, u.name;
+ uid | name
+-----+------
+(0 rows)
+
+-- OK
+SELECT u.uid, u.name FROM node n
+INNER JOIN users u ON u.uid = n.uid
+WHERE n.type = 'blog' AND n.status = 1
+GROUP BY u.uid;
+ uid | name
+-----+------
+(0 rows)
+
+-- Check views and dependencies
+-- fail
+CREATE TEMP VIEW fdv1 AS
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY body;
+ERROR: column "articles.id" must appear in the GROUP BY clause or be used in an aggregate function
+LINE 2: SELECT id, keywords, title, body, created
+ ^
+-- OK
+CREATE TEMP VIEW fdv1 AS
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY id;
+-- fail
+ALTER TABLE articles DROP CONSTRAINT articles_pkey RESTRICT;
+ERROR: cannot drop constraint articles_pkey on table articles because other objects depend on it
+DETAIL: view fdv1 depends on constraint articles_pkey on table articles
+HINT: Use DROP ... CASCADE to drop the dependent objects too.
+DROP VIEW fdv1;
+-- multiple dependencies
+CREATE TEMP VIEW fdv2 AS
+SELECT a.id, a.keywords, a.title, aic.category_id, aic.changed
+FROM articles AS a JOIN articles_in_category AS aic ON a.id = aic.article_id
+WHERE aic.category_id in (14,62,70,53,138)
+GROUP BY a.id, aic.category_id, aic.article_id;
+ALTER TABLE articles DROP CONSTRAINT articles_pkey RESTRICT; -- fail
+ERROR: cannot drop constraint articles_pkey on table articles because other objects depend on it
+DETAIL: view fdv2 depends on constraint articles_pkey on table articles
+HINT: Use DROP ... CASCADE to drop the dependent objects too.
+ALTER TABLE articles_in_category DROP CONSTRAINT articles_in_category_pkey RESTRICT; --fail
+ERROR: cannot drop constraint articles_in_category_pkey on table articles_in_category because other objects depend on it
+DETAIL: view fdv2 depends on constraint articles_in_category_pkey on table articles_in_category
+HINT: Use DROP ... CASCADE to drop the dependent objects too.
+DROP VIEW fdv2;
+-- nested queries
+CREATE TEMP VIEW fdv3 AS
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY id
+UNION
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY id;
+ALTER TABLE articles DROP CONSTRAINT articles_pkey RESTRICT; -- fail
+ERROR: cannot drop constraint articles_pkey on table articles because other objects depend on it
+DETAIL: view fdv3 depends on constraint articles_pkey on table articles
+HINT: Use DROP ... CASCADE to drop the dependent objects too.
+DROP VIEW fdv3;
+CREATE TEMP VIEW fdv4 AS
+SELECT * FROM articles WHERE title IN (SELECT title FROM articles GROUP BY id);
+ALTER TABLE articles DROP CONSTRAINT articles_pkey RESTRICT; -- fail
+ERROR: cannot drop constraint articles_pkey on table articles because other objects depend on it
+DETAIL: view fdv4 depends on constraint articles_pkey on table articles
+HINT: Use DROP ... CASCADE to drop the dependent objects too.
+DROP VIEW fdv4;
+-- prepared query plans: this results in failure on reuse
+PREPARE foo AS
+ SELECT id, keywords, title, body, created
+ FROM articles
+ GROUP BY id;
+EXECUTE foo;
+ id | keywords | title | body | created
+----+----------+-------+------+---------
+(0 rows)
+
+ALTER TABLE articles DROP CONSTRAINT articles_pkey RESTRICT;
+EXECUTE foo; -- fail
+ERROR: column "articles.keywords" must appear in the GROUP BY clause or be used in an aggregate function
# ----------
-# $PostgreSQL: pgsql/src/test/regress/parallel_schedule,v 1.61 2010/02/12 17:33:21 tgl Exp $
+# $PostgreSQL: pgsql/src/test/regress/parallel_schedule,v 1.62 2010/08/07 02:44:08 tgl Exp $
#
# By convention, we put no more than twenty tests in any one parallel group;
# this limits the number of connections needed to run the tests.
# ----------
# Another group of parallel tests
# ----------
-test: select_views portals_p2 foreign_key cluster dependency guc bitmapops combocid tsearch tsdicts foreign_data window xmlmap
+test: select_views portals_p2 foreign_key cluster dependency guc bitmapops combocid tsearch tsdicts foreign_data window xmlmap functional_deps
# ----------
# Another group of parallel tests
-# $PostgreSQL: pgsql/src/test/regress/serial_schedule,v 1.56 2010/02/12 17:33:21 tgl Exp $
+# $PostgreSQL: pgsql/src/test/regress/serial_schedule,v 1.57 2010/08/07 02:44:08 tgl Exp $
# This should probably be in an order similar to parallel_schedule.
test: tablespace
test: boolean
test: foreign_data
test: window
test: xmlmap
+test: functional_deps
test: plancache
test: limit
test: plpgsql
--- /dev/null
+-- from http://www.depesz.com/index.php/2010/04/19/getting-unique-elements/
+
+CREATE TEMP TABLE articles (
+ id int CONSTRAINT articles_pkey PRIMARY KEY,
+ keywords text,
+ title text UNIQUE NOT NULL,
+ body text UNIQUE,
+ created date
+);
+
+CREATE TEMP TABLE articles_in_category (
+ article_id int,
+ category_id int,
+ changed date,
+ PRIMARY KEY (article_id, category_id)
+);
+
+-- test functional dependencies based on primary keys/unique constraints
+
+-- base tables
+
+-- group by primary key (OK)
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY id;
+
+-- group by unique not null (fail/todo)
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY title;
+
+-- group by unique nullable (fail)
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY body;
+
+-- group by something else (fail)
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY keywords;
+
+-- multiple tables
+
+-- group by primary key (OK)
+SELECT a.id, a.keywords, a.title, a.body, a.created
+FROM articles AS a, articles_in_category AS aic
+WHERE a.id = aic.article_id AND aic.category_id in (14,62,70,53,138)
+GROUP BY a.id;
+
+-- group by something else (fail)
+SELECT a.id, a.keywords, a.title, a.body, a.created
+FROM articles AS a, articles_in_category AS aic
+WHERE a.id = aic.article_id AND aic.category_id in (14,62,70,53,138)
+GROUP BY aic.article_id, aic.category_id;
+
+-- JOIN syntax
+
+-- group by left table's primary key (OK)
+SELECT a.id, a.keywords, a.title, a.body, a.created
+FROM articles AS a JOIN articles_in_category AS aic ON a.id = aic.article_id
+WHERE aic.category_id in (14,62,70,53,138)
+GROUP BY a.id;
+
+-- group by something else (fail)
+SELECT a.id, a.keywords, a.title, a.body, a.created
+FROM articles AS a JOIN articles_in_category AS aic ON a.id = aic.article_id
+WHERE aic.category_id in (14,62,70,53,138)
+GROUP BY aic.article_id, aic.category_id;
+
+-- group by right table's (composite) primary key (OK)
+SELECT aic.changed
+FROM articles AS a JOIN articles_in_category AS aic ON a.id = aic.article_id
+WHERE aic.category_id in (14,62,70,53,138)
+GROUP BY aic.category_id, aic.article_id;
+
+-- group by right table's partial primary key (fail)
+SELECT aic.changed
+FROM articles AS a JOIN articles_in_category AS aic ON a.id = aic.article_id
+WHERE aic.category_id in (14,62,70,53,138)
+GROUP BY aic.article_id;
+
+
+-- example from documentation
+
+CREATE TEMP TABLE products (product_id int, name text, price numeric);
+CREATE TEMP TABLE sales (product_id int, units int);
+
+-- OK
+SELECT product_id, p.name, (sum(s.units) * p.price) AS sales
+ FROM products p LEFT JOIN sales s USING (product_id)
+ GROUP BY product_id, p.name, p.price;
+
+-- fail
+SELECT product_id, p.name, (sum(s.units) * p.price) AS sales
+ FROM products p LEFT JOIN sales s USING (product_id)
+ GROUP BY product_id;
+
+ALTER TABLE products ADD PRIMARY KEY (product_id);
+
+-- OK now
+SELECT product_id, p.name, (sum(s.units) * p.price) AS sales
+ FROM products p LEFT JOIN sales s USING (product_id)
+ GROUP BY product_id;
+
+
+-- Drupal example, http://drupal.org/node/555530
+
+CREATE TEMP TABLE node (
+ nid SERIAL,
+ vid integer NOT NULL default '0',
+ type varchar(32) NOT NULL default '',
+ title varchar(128) NOT NULL default '',
+ uid integer NOT NULL default '0',
+ status integer NOT NULL default '1',
+ created integer NOT NULL default '0',
+ -- snip
+ PRIMARY KEY (nid, vid)
+);
+
+CREATE TEMP TABLE users (
+ uid integer NOT NULL default '0',
+ name varchar(60) NOT NULL default '',
+ pass varchar(32) NOT NULL default '',
+ -- snip
+ PRIMARY KEY (uid),
+ UNIQUE (name)
+);
+
+-- OK
+SELECT u.uid, u.name FROM node n
+INNER JOIN users u ON u.uid = n.uid
+WHERE n.type = 'blog' AND n.status = 1
+GROUP BY u.uid, u.name;
+
+-- OK
+SELECT u.uid, u.name FROM node n
+INNER JOIN users u ON u.uid = n.uid
+WHERE n.type = 'blog' AND n.status = 1
+GROUP BY u.uid;
+
+
+-- Check views and dependencies
+
+-- fail
+CREATE TEMP VIEW fdv1 AS
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY body;
+
+-- OK
+CREATE TEMP VIEW fdv1 AS
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY id;
+
+-- fail
+ALTER TABLE articles DROP CONSTRAINT articles_pkey RESTRICT;
+
+DROP VIEW fdv1;
+
+
+-- multiple dependencies
+CREATE TEMP VIEW fdv2 AS
+SELECT a.id, a.keywords, a.title, aic.category_id, aic.changed
+FROM articles AS a JOIN articles_in_category AS aic ON a.id = aic.article_id
+WHERE aic.category_id in (14,62,70,53,138)
+GROUP BY a.id, aic.category_id, aic.article_id;
+
+ALTER TABLE articles DROP CONSTRAINT articles_pkey RESTRICT; -- fail
+ALTER TABLE articles_in_category DROP CONSTRAINT articles_in_category_pkey RESTRICT; --fail
+
+DROP VIEW fdv2;
+
+
+-- nested queries
+
+CREATE TEMP VIEW fdv3 AS
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY id
+UNION
+SELECT id, keywords, title, body, created
+FROM articles
+GROUP BY id;
+
+ALTER TABLE articles DROP CONSTRAINT articles_pkey RESTRICT; -- fail
+
+DROP VIEW fdv3;
+
+
+CREATE TEMP VIEW fdv4 AS
+SELECT * FROM articles WHERE title IN (SELECT title FROM articles GROUP BY id);
+
+ALTER TABLE articles DROP CONSTRAINT articles_pkey RESTRICT; -- fail
+
+DROP VIEW fdv4;
+
+
+-- prepared query plans: this results in failure on reuse
+
+PREPARE foo AS
+ SELECT id, keywords, title, body, created
+ FROM articles
+ GROUP BY id;
+
+EXECUTE foo;
+
+ALTER TABLE articles DROP CONSTRAINT articles_pkey RESTRICT;
+
+EXECUTE foo; -- fail
projects / postgresql / commitdiff