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Attached are two patches to implement and document anonymous composite
types for Table Functions, as previously proposed on HACKERS. Here is a
brief explanation:
1. Creates a new pg_type typtype: 'p' for pseudo type (currently either
'b' for base or 'c' for catalog, i.e. a class).
2. Creates new builtin type of typtype='p' named RECORD. This is the
first of potentially several pseudo types.
3. Modify FROM clause grammer to accept:
SELECT * FROM my_func() AS m(colname1 type1, colname2 type1, ...)
where m is the table alias, colname1, etc are the column names, and
type1, etc are the column types.
4. When typtype == 'p' and the function return type is RECORD, a list
of column defs is required, and when typtype != 'p', it is
disallowed.
5. A check was added to ensure that the tupdesc provide via the parser
and the actual return tupdesc match in number and type of
attributes.
When creating a function you can do:
CREATE FUNCTION foo(text) RETURNS setof RECORD ...
When using it you can do:
SELECT * from foo(sqlstmt) AS (f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) AS f(f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) f(f1 int, f2 text, f3 timestamp)
Included in the patches are adjustments to the regression test sql and
expected files, and documentation.
p.s.
This potentially solves (or at least improves) the issue of builtin
Table Functions. They can be bootstrapped as returning RECORD, and
we can wrap system views around them with properly specified column
defs. For example:
CREATE VIEW pg_settings AS
SELECT s.name, s.setting
FROM show_all_settings()AS s(name text, setting text);
Then we can also add the UPDATE RULE that I previously posted to
pg_settings, and have pg_settings act like a virtual table, allowing
settings to be queried and set.
Joe Conway
This commit is contained in:
Bruce Momjian
@@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/catalog/pg_proc.c,v 1.82 2002/08/02 18:15:05 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/catalog/pg_proc.c,v 1.83 2002/08/04 19:48:09 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@@ -25,6 +25,7 @@
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#include "miscadmin.h"
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#include "parser/parse_coerce.h"
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#include "parser/parse_expr.h"
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#include "parser/parse_relation.h"
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#include "parser/parse_type.h"
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#include "tcop/tcopprot.h"
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#include "utils/builtins.h"
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@@ -33,7 +34,7 @@
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#include "utils/syscache.h"
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static void checkretval(Oid rettype, List *queryTreeList);
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static void checkretval(Oid rettype, char fn_typtype, List *queryTreeList);
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Datum fmgr_internal_validator(PG_FUNCTION_ARGS);
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Datum fmgr_c_validator(PG_FUNCTION_ARGS);
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Datum fmgr_sql_validator(PG_FUNCTION_ARGS);
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@@ -367,94 +368,113 @@ checkretval(Oid rettype, List *queryTreeList)
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*/
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tlistlen = ExecCleanTargetListLength(tlist);
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/*
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* For base-type returns, the target list should have exactly one
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* entry, and its type should agree with what the user declared. (As
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* of Postgres 7.2, we accept binary-compatible types too.)
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*/
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typerelid = typeidTypeRelid(rettype);
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if (typerelid == InvalidOid)
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{
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if (tlistlen != 1)
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elog(ERROR, "function declared to return %s returns multiple columns in final SELECT",
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format_type_be(rettype));
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restype = ((TargetEntry *) lfirst(tlist))->resdom->restype;
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if (!IsBinaryCompatible(restype, rettype))
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elog(ERROR, "return type mismatch in function: declared to return %s, returns %s",
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format_type_be(rettype), format_type_be(restype));
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if (fn_typtype == 'b')
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{
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/*
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* For base-type returns, the target list should have exactly one
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* entry, and its type should agree with what the user declared. (As
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* of Postgres 7.2, we accept binary-compatible types too.)
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*/
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if (typerelid == InvalidOid)
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{
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if (tlistlen != 1)
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elog(ERROR, "function declared to return %s returns multiple columns in final SELECT",
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format_type_be(rettype));
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restype = ((TargetEntry *) lfirst(tlist))->resdom->restype;
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if (!IsBinaryCompatible(restype, rettype))
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elog(ERROR, "return type mismatch in function: declared to return %s, returns %s",
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format_type_be(rettype), format_type_be(restype));
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return;
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}
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/*
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* If the target list is of length 1, and the type of the varnode in
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* the target list matches the declared return type, this is okay.
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* This can happen, for example, where the body of the function is
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* 'SELECT func2()', where func2 has the same return type as the
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* function that's calling it.
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*/
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if (tlistlen == 1)
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{
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restype = ((TargetEntry *) lfirst(tlist))->resdom->restype;
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if (IsBinaryCompatible(restype, rettype))
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return;
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}
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}
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else if (fn_typtype == 'c')
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{
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/*
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* By here, the procedure returns a tuple or set of tuples. This part
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* of the typechecking is a hack. We look up the relation that is the
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* declared return type, and scan the non-deleted attributes to ensure
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* that they match the datatypes of the non-resjunk columns.
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*/
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reln = heap_open(typerelid, AccessShareLock);
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relnatts = reln->rd_rel->relnatts;
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rellogcols = 0; /* we'll count nondeleted cols as we go */
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colindex = 0;
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foreach(tlistitem, tlist)
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{
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TargetEntry *tle = (TargetEntry *) lfirst(tlistitem);
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Form_pg_attribute attr;
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Oid tletype;
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Oid atttype;
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if (tle->resdom->resjunk)
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continue;
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do {
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colindex++;
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if (colindex > relnatts)
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elog(ERROR, "function declared to return %s does not SELECT the right number of columns (%d)",
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format_type_be(rettype), rellogcols);
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attr = reln->rd_att->attrs[colindex - 1];
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} while (attr->attisdropped);
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rellogcols++;
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tletype = exprType(tle->expr);
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atttype = attr->atttypid;
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if (!IsBinaryCompatible(tletype, atttype))
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elog(ERROR, "function declared to return %s returns %s instead of %s at column %d",
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format_type_be(rettype),
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format_type_be(tletype),
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format_type_be(atttype),
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rellogcols);
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}
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for (;;)
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{
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colindex++;
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if (colindex > relnatts)
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break;
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if (!reln->rd_att->attrs[colindex - 1]->attisdropped)
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rellogcols++;
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}
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if (tlistlen != rellogcols)
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elog(ERROR, "function declared to return %s does not SELECT the right number of columns (%d)",
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format_type_be(rettype), rellogcols);
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heap_close(reln, AccessShareLock);
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return;
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}
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/*
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* If the target list is of length 1, and the type of the varnode in
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* the target list matches the declared return type, this is okay.
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* This can happen, for example, where the body of the function is
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* 'SELECT func2()', where func2 has the same return type as the
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* function that's calling it.
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*/
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if (tlistlen == 1)
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else if (fn_typtype == 'p' && rettype == RECORDOID)
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{
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restype = ((TargetEntry *) lfirst(tlist))->resdom->restype;
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if (IsBinaryCompatible(restype, rettype))
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return;
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/*
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* For RECORD return type, defer this check until we get the
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* first tuple.
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*/
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return;
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}
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/*
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* By here, the procedure returns a tuple or set of tuples. This part
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* of the typechecking is a hack. We look up the relation that is the
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* declared return type, and scan the non-deleted attributes to ensure
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* that they match the datatypes of the non-resjunk columns.
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*/
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reln = heap_open(typerelid, AccessShareLock);
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relnatts = reln->rd_rel->relnatts;
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rellogcols = 0; /* we'll count nondeleted cols as we go */
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colindex = 0;
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foreach(tlistitem, tlist)
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{
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TargetEntry *tle = (TargetEntry *) lfirst(tlistitem);
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Form_pg_attribute attr;
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Oid tletype;
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Oid atttype;
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if (tle->resdom->resjunk)
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continue;
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do {
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colindex++;
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if (colindex > relnatts)
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elog(ERROR, "function declared to return %s does not SELECT the right number of columns (%d)",
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format_type_be(rettype), rellogcols);
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attr = reln->rd_att->attrs[colindex - 1];
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} while (attr->attisdropped);
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rellogcols++;
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tletype = exprType(tle->expr);
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atttype = attr->atttypid;
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if (!IsBinaryCompatible(tletype, atttype))
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elog(ERROR, "function declared to return %s returns %s instead of %s at column %d",
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format_type_be(rettype),
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format_type_be(tletype),
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format_type_be(atttype),
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rellogcols);
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}
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for (;;)
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{
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colindex++;
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if (colindex > relnatts)
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break;
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if (!reln->rd_att->attrs[colindex - 1]->attisdropped)
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rellogcols++;
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}
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if (tlistlen != rellogcols)
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elog(ERROR, "function declared to return %s does not SELECT the right number of columns (%d)",
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format_type_be(rettype), rellogcols);
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heap_close(reln, AccessShareLock);
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else
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elog(ERROR, "Unknown kind of return type specified for function");
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}
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@@ -553,6 +573,7 @@ fmgr_sql_validator(PG_FUNCTION_ARGS)
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bool isnull;
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Datum tmp;
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char *prosrc;
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char functyptype;
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tuple = SearchSysCache(PROCOID, funcoid, 0, 0, 0);
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if (!HeapTupleIsValid(tuple))
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@@ -569,8 +590,11 @@ fmgr_sql_validator(PG_FUNCTION_ARGS)
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prosrc = DatumGetCString(DirectFunctionCall1(textout, tmp));
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/* check typtype to see if we have a predetermined return type */
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functyptype = typeid_get_typtype(proc->prorettype);
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querytree_list = pg_parse_and_rewrite(prosrc, proc->proargtypes, proc->pronargs);
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checkretval(proc->prorettype, querytree_list);
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checkretval(proc->prorettype, functyptype, querytree_list);
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ReleaseSysCache(tuple);
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PG_RETURN_BOOL(true);
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