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Add result_types column to pg_prepared_statements view
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Containing the types of the columns returned by the prepared
statement.

Prompted by question from IRC user mlvzk.

Author: Dagfinn Ilmari Mannsåker <ilmari@ilmari.org>
Discussion: https://www.postgresql.org/message-id/flat/871qwpo7te.fsf@wibble.ilmari.org
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@petere
petere committed Jul 5, 2022
1 parent eb64cea commit 84ad713
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Showing 7 changed files with 74 additions and 52 deletions.
12 changes: 12 additions & 0 deletions doc/src/sgml/catalogs.sgml
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Expand Up @@ -11502,6 +11502,18 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx
</para></entry>
</row>

<row>
<entry role="catalog_table_entry"><para role="column_definition">
<structfield>result_types</structfield> <type>regtype[]</type>
</para>
<para>
The types of the columns returned by the prepared statement in the
form of an array of <type>regtype</type>. The OID corresponding
to an element of this array can be obtained by casting the
<type>regtype</type> value to <type>oid</type>.
</para></entry>
</row>

<row>
<entry role="catalog_table_entry"><para role="column_definition">
<structfield>from_sql</structfield> <type>bool</type>
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19 changes: 14 additions & 5 deletions src/backend/commands/prepare.c
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Original file line number Diff line number Diff line change
Expand Up @@ -683,8 +683,16 @@ pg_prepared_statement(PG_FUNCTION_ARGS)
hash_seq_init(&hash_seq, prepared_queries);
while ((prep_stmt = hash_seq_search(&hash_seq)) != NULL)
{
Datum values[7];
bool nulls[7];
TupleDesc result_desc;
Oid *result_types;
Datum values[8];
bool nulls[8];

result_desc = prep_stmt->plansource->resultDesc;
result_types = (Oid *) palloc(result_desc->natts * sizeof(Oid));

for (int i = 0; i < result_desc->natts; i++)
result_types[i] = result_desc->attrs[i].atttypid;

MemSet(nulls, 0, sizeof(nulls));

Expand All @@ -693,9 +701,10 @@ pg_prepared_statement(PG_FUNCTION_ARGS)
values[2] = TimestampTzGetDatum(prep_stmt->prepare_time);
values[3] = build_regtype_array(prep_stmt->plansource->param_types,
prep_stmt->plansource->num_params);
values[4] = BoolGetDatum(prep_stmt->from_sql);
values[5] = Int64GetDatumFast(prep_stmt->plansource->num_generic_plans);
values[6] = Int64GetDatumFast(prep_stmt->plansource->num_custom_plans);
values[4] = build_regtype_array(result_types, result_desc->natts);
values[5] = BoolGetDatum(prep_stmt->from_sql);
values[6] = Int64GetDatumFast(prep_stmt->plansource->num_generic_plans);
values[7] = Int64GetDatumFast(prep_stmt->plansource->num_custom_plans);

tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc,
values, nulls);
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2 changes: 1 addition & 1 deletion src/include/catalog/catversion.h
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Expand Up @@ -53,6 +53,6 @@
*/

/* yyyymmddN */
#define CATALOG_VERSION_NO 202205191
#define CATALOG_VERSION_NO 202207051

#endif
6 changes: 3 additions & 3 deletions src/include/catalog/pg_proc.dat
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Expand Up @@ -8025,9 +8025,9 @@
proname => 'pg_prepared_statement', prorows => '1000', proretset => 't',
provolatile => 's', proparallel => 'r', prorettype => 'record',
proargtypes => '',
proallargtypes => '{text,text,timestamptz,_regtype,bool,int8,int8}',
proargmodes => '{o,o,o,o,o,o,o}',
proargnames => '{name,statement,prepare_time,parameter_types,from_sql,generic_plans,custom_plans}',
proallargtypes => '{text,text,timestamptz,_regtype,_regtype,bool,int8,int8}',
proargmodes => '{o,o,o,o,o,o,o,o}',
proargnames => '{name,statement,prepare_time,parameter_types,result_types,from_sql,generic_plans,custom_plans}',
prosrc => 'pg_prepared_statement' },
{ oid => '2511', descr => 'get the open cursors for this session',
proname => 'pg_cursor', prorows => '1000', proretset => 't',
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72 changes: 36 additions & 36 deletions src/test/regress/expected/prepare.out
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Original file line number Diff line number Diff line change
@@ -1,9 +1,9 @@
-- Regression tests for prepareable statements. We query the content
-- of the pg_prepared_statements view as prepared statements are
-- created and removed.
SELECT name, statement, parameter_types FROM pg_prepared_statements;
name | statement | parameter_types
------+-----------+-----------------
SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements;
name | statement | parameter_types | result_types
------+-----------+-----------------+--------------
(0 rows)

PREPARE q1 AS SELECT 1 AS a;
Expand All @@ -13,10 +13,10 @@ EXECUTE q1;
1
(1 row)

SELECT name, statement, parameter_types FROM pg_prepared_statements;
name | statement | parameter_types
------+------------------------------+-----------------
q1 | PREPARE q1 AS SELECT 1 AS a; | {}
SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements;
name | statement | parameter_types | result_types
------+------------------------------+-----------------+--------------
q1 | PREPARE q1 AS SELECT 1 AS a; | {} | {integer}
(1 row)

-- should fail
Expand All @@ -32,26 +32,26 @@ EXECUTE q1;
(1 row)

PREPARE q2 AS SELECT 2 AS b;
SELECT name, statement, parameter_types FROM pg_prepared_statements;
name | statement | parameter_types
------+------------------------------+-----------------
q1 | PREPARE q1 AS SELECT 2; | {}
q2 | PREPARE q2 AS SELECT 2 AS b; | {}
SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements;
name | statement | parameter_types | result_types
------+------------------------------+-----------------+--------------
q1 | PREPARE q1 AS SELECT 2; | {} | {integer}
q2 | PREPARE q2 AS SELECT 2 AS b; | {} | {integer}
(2 rows)

-- sql92 syntax
DEALLOCATE PREPARE q1;
SELECT name, statement, parameter_types FROM pg_prepared_statements;
name | statement | parameter_types
------+------------------------------+-----------------
q2 | PREPARE q2 AS SELECT 2 AS b; | {}
SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements;
name | statement | parameter_types | result_types
------+------------------------------+-----------------+--------------
q2 | PREPARE q2 AS SELECT 2 AS b; | {} | {integer}
(1 row)

DEALLOCATE PREPARE q2;
-- the view should return the empty set again
SELECT name, statement, parameter_types FROM pg_prepared_statements;
name | statement | parameter_types
------+-----------+-----------------
SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements;
name | statement | parameter_types | result_types
------+-----------+-----------------+--------------
(0 rows)

-- parameterized queries
Expand Down Expand Up @@ -159,24 +159,24 @@ PREPARE q6 AS
SELECT * FROM tenk1 WHERE unique1 = $1 AND stringu1 = $2;
PREPARE q7(unknown) AS
SELECT * FROM road WHERE thepath = $1;
SELECT name, statement, parameter_types FROM pg_prepared_statements
SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements
ORDER BY name;
name | statement | parameter_types
------+------------------------------------------------------------------+----------------------------------------------------
q2 | PREPARE q2(text) AS +| {text}
| SELECT datname, datistemplate, datallowconn +|
| FROM pg_database WHERE datname = $1; |
q3 | PREPARE q3(text, int, float, boolean, smallint) AS +| {text,integer,"double precision",boolean,smallint}
| SELECT * FROM tenk1 WHERE string4 = $1 AND (four = $2 OR+|
| ten = $3::bigint OR true = $4 OR odd = $5::int) +|
| ORDER BY unique1; |
q5 | PREPARE q5(int, text) AS +| {integer,text}
| SELECT * FROM tenk1 WHERE unique1 = $1 OR stringu1 = $2 +|
| ORDER BY unique1; |
q6 | PREPARE q6 AS +| {integer,name}
| SELECT * FROM tenk1 WHERE unique1 = $1 AND stringu1 = $2; |
q7 | PREPARE q7(unknown) AS +| {path}
| SELECT * FROM road WHERE thepath = $1; |
name | statement | parameter_types | result_types
------+------------------------------------------------------------------+----------------------------------------------------+--------------------------------------------------------------------------------------------------------------------------
q2 | PREPARE q2(text) AS +| {text} | {name,boolean,boolean}
| SELECT datname, datistemplate, datallowconn +| |
| FROM pg_database WHERE datname = $1; | |
q3 | PREPARE q3(text, int, float, boolean, smallint) AS +| {text,integer,"double precision",boolean,smallint} | {integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,name,name,name}
| SELECT * FROM tenk1 WHERE string4 = $1 AND (four = $2 OR+| |
| ten = $3::bigint OR true = $4 OR odd = $5::int) +| |
| ORDER BY unique1; | |
q5 | PREPARE q5(int, text) AS +| {integer,text} | {integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,name,name,name}
| SELECT * FROM tenk1 WHERE unique1 = $1 OR stringu1 = $2 +| |
| ORDER BY unique1; | |
q6 | PREPARE q6 AS +| {integer,name} | {integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,name,name,name}
| SELECT * FROM tenk1 WHERE unique1 = $1 AND stringu1 = $2; | |
q7 | PREPARE q7(unknown) AS +| {path} | {text,path}
| SELECT * FROM road WHERE thepath = $1; | |
(5 rows)

-- test DEALLOCATE ALL;
Expand Down
3 changes: 2 additions & 1 deletion src/test/regress/expected/rules.out
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Original file line number Diff line number Diff line change
Expand Up @@ -1423,10 +1423,11 @@ pg_prepared_statements| SELECT p.name,
p.statement,
p.prepare_time,
p.parameter_types,
p.result_types,
p.from_sql,
p.generic_plans,
p.custom_plans
FROM pg_prepared_statement() p(name, statement, prepare_time, parameter_types, from_sql, generic_plans, custom_plans);
FROM pg_prepared_statement() p(name, statement, prepare_time, parameter_types, result_types, from_sql, generic_plans, custom_plans);
pg_prepared_xacts| SELECT p.transaction,
p.gid,
p.prepared,
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12 changes: 6 additions & 6 deletions src/test/regress/sql/prepare.sql
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Original file line number Diff line number Diff line change
Expand Up @@ -2,12 +2,12 @@
-- of the pg_prepared_statements view as prepared statements are
-- created and removed.

SELECT name, statement, parameter_types FROM pg_prepared_statements;
SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements;

PREPARE q1 AS SELECT 1 AS a;
EXECUTE q1;

SELECT name, statement, parameter_types FROM pg_prepared_statements;
SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements;

-- should fail
PREPARE q1 AS SELECT 2;
Expand All @@ -18,16 +18,16 @@ PREPARE q1 AS SELECT 2;
EXECUTE q1;

PREPARE q2 AS SELECT 2 AS b;
SELECT name, statement, parameter_types FROM pg_prepared_statements;
SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements;

-- sql92 syntax
DEALLOCATE PREPARE q1;

SELECT name, statement, parameter_types FROM pg_prepared_statements;
SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements;

DEALLOCATE PREPARE q2;
-- the view should return the empty set again
SELECT name, statement, parameter_types FROM pg_prepared_statements;
SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements;

-- parameterized queries
PREPARE q2(text) AS
Expand Down Expand Up @@ -71,7 +71,7 @@ PREPARE q6 AS
PREPARE q7(unknown) AS
SELECT * FROM road WHERE thepath = $1;

SELECT name, statement, parameter_types FROM pg_prepared_statements
SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements
ORDER BY name;

-- test DEALLOCATE ALL;
Expand Down

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