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As discussed on several occasions previously, the new anonymous

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composite type capability makes it possible to create a system view
based on a table function in a way that is hopefully palatable to
everyone. The attached patch takes advantage of this, moving
show_all_settings() from contrib/tablefunc into the backend (renamed
all_settings(). It is defined as a builtin returning type RECORD. During
initdb a system view is created to expose the same information presently
available through SHOW ALL. For example:

test=# select * from pg_settings where name like '%debug%';
          name          | setting
-----------------------+---------
  debug_assertions      | on
  debug_pretty_print    | off
  debug_print_parse     | off
  debug_print_plan      | off
  debug_print_query     | off
  debug_print_rewritten | off
  wal_debug             | 0
(7 rows)


Additionally during initdb two rules are created which make it possible
to change settings by updating the system view -- a "virtual table" as
Tom put it. Here's an example:

Joe Conway
This commit is contained in:
Bruce Momjian
2002-08-15 02:51:27 +00:00
parent 4c4854c458
commit 45e2544584
10 changed files with 372 additions and 220 deletions
Download Patch File Download Diff File Expand all files Collapse all files

139
contrib/tablefunc/README.tablefunc
View File

@ -46,9 +46,6 @@ Installation:
installs following functions into database template1:
show_all_settings()
- returns the same information as SHOW ALL, but as a query result
normal_rand(int numvals, float8 mean, float8 stddev, int seed)
- returns a set of normally distributed float8 values
@ -58,48 +55,15 @@ Installation:
but you can create additional crosstab functions per the instructions
in the documentation below.
crosstab(text sql, N int)
- returns a set of row_name plus N category value columns
- requires anonymous composite type syntax in the FROM clause. See
the instructions in the documentation below.
Documentation
==================================================================
Name
show_all_settings() - returns the same information as SHOW ALL,
but as a query result.
Synopsis
show_all_settings()
Inputs
none
Outputs
Returns setof tablefunc_config_settings which is defined by:
CREATE VIEW tablefunc_config_settings AS
SELECT
''::TEXT AS name,
''::TEXT AS setting;
Example usage
test=# select * from show_all_settings();
name | setting
-------------------------------+---------------------------------------
australian_timezones | off
authentication_timeout | 60
checkpoint_segments | 3
.
.
.
wal_debug | 0
wal_files | 0
wal_sync_method | fdatasync
(94 rows)
==================================================================
Name
normal_rand(int, float8, float8, int) - returns a set of normally
distributed float8 values
@ -267,6 +231,99 @@ select * from crosstab3(
test2 | val6 | val7 |
(2 rows)
==================================================================
Name
crosstab(text, int) - returns a set of row_name
plus N category value columns
Synopsis
crosstab(text sql, int N)
Inputs
sql
A SQL statement which produces the source set of data. The SQL statement
must return one row_name column, one category column, and one value
column.
e.g. provided sql must produce a set something like:
row_name cat value
----------+-------+-------
row1 cat1 val1
row1 cat2 val2
row1 cat3 val3
row1 cat4 val4
row2 cat1 val5
row2 cat2 val6
row2 cat3 val7
row2 cat4 val8
N
number of category value columns
Outputs
Returns setof record, which must defined with a column definition
in the FROM clause of the SELECT statement, e.g.:
SELECT *
FROM crosstab(sql, 2) AS ct(row_name text, category_1 text, category_2 text);
the example crosstab function produces a set something like:
<== values columns ==>
row_name category_1 category_2
---------+------------+------------
row1 val1 val2
row2 val5 val6
Notes
1. The sql result must be ordered by 1,2.
2. The number of values columns is determined at run-time. The
column definition provided in the FROM clause must provide for
N + 1 columns of the proper data types.
3. Missing values (i.e. not enough adjacent rows of same row_name to
fill the number of result values columns) are filled in with nulls.
4. Extra values (i.e. too many adjacent rows of same row_name to fill
the number of result values columns) are skipped.
5. Rows with all nulls in the values columns are skipped.
Example usage
create table ct(id serial, rowclass text, rowid text, attribute text, value text);
insert into ct(rowclass, rowid, attribute, value) values('group1','test1','att1','val1');
insert into ct(rowclass, rowid, attribute, value) values('group1','test1','att2','val2');
insert into ct(rowclass, rowid, attribute, value) values('group1','test1','att3','val3');
insert into ct(rowclass, rowid, attribute, value) values('group1','test1','att4','val4');
insert into ct(rowclass, rowid, attribute, value) values('group1','test2','att1','val5');
insert into ct(rowclass, rowid, attribute, value) values('group1','test2','att2','val6');
insert into ct(rowclass, rowid, attribute, value) values('group1','test2','att3','val7');
insert into ct(rowclass, rowid, attribute, value) values('group1','test2','att4','val8');
SELECT *
FROM crosstab(
'select rowid, attribute, value
from ct
where rowclass = ''group1''
and (attribute = ''att2'' or attribute = ''att3'') order by 1,2;', 3)
AS ct(row_name text, category_1 text, category_2 text, category_3 text);
row_name | category_1 | category_2 | category_3
----------+------------+------------+------------
test1 | val2 | val3 |
test2 | val6 | val7 |
(2 rows)
==================================================================
-- Joe Conway

4
contrib/tablefunc/tablefunc-test.sql
View File

@ -44,4 +44,6 @@ select * from crosstab2('select rowid, attribute, value from ct where rowclass =
select * from crosstab3('select rowid, attribute, value from ct where rowclass = ''group2'' order by 1,2;');
select * from crosstab4('select rowid, attribute, value from ct where rowclass = ''group2'' order by 1,2;');
select * from crosstab('select rowid, attribute, value from ct where rowclass = ''group1'' order by 1,2;', 2) as c(rowid text, att1 text, att2 text);
select * from crosstab('select rowid, attribute, value from ct where rowclass = ''group1'' order by 1,2;', 3) as c(rowid text, att1 text, att2 text, att3 text);
select * from crosstab('select rowid, attribute, value from ct where rowclass = ''group1'' order by 1,2;', 4) as c(rowid text, att1 text, att2 text, att3 text, att4 text);

291
contrib/tablefunc/tablefunc.c
View File

@ -35,11 +35,13 @@
#include "executor/spi.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/lsyscache.h"
#include "tablefunc.h"
static bool compatTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2);
static void get_normal_pair(float8 *x1, float8 *x2);
static TupleDesc make_crosstab_tupledesc(TupleDesc spi_tupdesc, int num_catagories);
typedef struct
{
@ -66,118 +68,6 @@ typedef struct
} \
} while (0)
/*
* show_all_settings - equiv to SHOW ALL command but implemented as
* a Table Function.
*/
PG_FUNCTION_INFO_V1(show_all_settings);
Datum
show_all_settings(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
TupleDesc tupdesc;
int call_cntr;
int max_calls;
TupleTableSlot *slot;
AttInMetadata *attinmeta;
/* stuff done only on the first call of the function */
if(SRF_IS_FIRSTCALL())
{
Oid foid = fcinfo->flinfo->fn_oid;
Oid functypeid;
/* create a function context for cross-call persistence */
funcctx = SRF_FIRSTCALL_INIT();
/* get the typeid that represents our return type */
functypeid = foidGetTypeId(foid);
/* Build a tuple description for a funcrelid tuple */
tupdesc = TypeGetTupleDesc(functypeid, NIL);
/* allocate a slot for a tuple with this tupdesc */
slot = TupleDescGetSlot(tupdesc);
/* assign slot to function context */
funcctx->slot = slot;
/*
* Generate attribute metadata needed later to produce tuples from raw
* C strings
*/
attinmeta = TupleDescGetAttInMetadata(tupdesc);
funcctx->attinmeta = attinmeta;
/* total number of tuples to be returned */
funcctx->max_calls = GetNumConfigOptions();
}
/* stuff done on every call of the function */
funcctx = SRF_PERCALL_SETUP();
call_cntr = funcctx->call_cntr;
max_calls = funcctx->max_calls;
slot = funcctx->slot;
attinmeta = funcctx->attinmeta;
if (call_cntr < max_calls) /* do when there is more left to send */
{
char **values;
char *varname;
char *varval;
bool noshow;
HeapTuple tuple;
Datum result;
/*
* Get the next visible GUC variable name and value
*/
do
{
varval = GetConfigOptionByNum(call_cntr, (const char **) &varname, &noshow);
if (noshow)
{
/* varval is a palloc'd copy, so free it */
xpfree(varval);
/* bump the counter and get the next config setting */
call_cntr = ++funcctx->call_cntr;
/* make sure we haven't gone too far now */
if (call_cntr >= max_calls)
SRF_RETURN_DONE(funcctx);
}
} while (noshow);
/*
* Prepare a values array for storage in our slot.
* This should be an array of C strings which will
* be processed later by the appropriate "in" functions.
*/
values = (char **) palloc(2 * sizeof(char *));
values[0] = pstrdup(varname);
values[1] = varval; /* varval is already a palloc'd copy */
/* build a tuple */
tuple = BuildTupleFromCStrings(attinmeta, values);
/* make the tuple into a datum */
result = TupleGetDatum(slot, tuple);
/* Clean up */
xpfree(values[0]);
xpfree(values[1]);
xpfree(values);
SRF_RETURN_NEXT(funcctx, result);
}
else /* do when there is no more left */
{
SRF_RETURN_DONE(funcctx);
}
}
/*
* normal_rand - return requested number of random values
* with a Gaussian (Normal) distribution.
@ -368,7 +258,7 @@ crosstab(PG_FUNCTION_ARGS)
int max_calls;
TupleTableSlot *slot;
AttInMetadata *attinmeta;
SPITupleTable *spi_tuptable;
SPITupleTable *spi_tuptable = NULL;
TupleDesc spi_tupdesc;
char *lastrowid;
crosstab_fctx *fctx;
@ -378,34 +268,20 @@ crosstab(PG_FUNCTION_ARGS)
/* stuff done only on the first call of the function */
if(SRF_IS_FIRSTCALL())
{
char *sql = GET_STR(PG_GETARG_TEXT_P(0));
Oid foid = fcinfo->flinfo->fn_oid;
Oid functypeid;
TupleDesc tupdesc;
int ret;
int proc;
char *sql = GET_STR(PG_GETARG_TEXT_P(0));
Oid funcid = fcinfo->flinfo->fn_oid;
Oid functypeid;
char functyptype;
TupleDesc tupdesc = NULL;
int ret;
int proc;
MemoryContext oldcontext;
/* create a function context for cross-call persistence */
funcctx = SRF_FIRSTCALL_INIT();
/* get the typeid that represents our return type */
functypeid = foidGetTypeId(foid);
/* Build a tuple description for a funcrelid tuple */
tupdesc = TypeGetTupleDesc(functypeid, NIL);
/* allocate a slot for a tuple with this tupdesc */
slot = TupleDescGetSlot(tupdesc);
/* assign slot to function context */
funcctx->slot = slot;
/*
* Generate attribute metadata needed later to produce tuples from raw
* C strings
*/
attinmeta = TupleDescGetAttInMetadata(tupdesc);
funcctx->attinmeta = attinmeta;
/* SPI switches context on us, so save it first */
oldcontext = CurrentMemoryContext;
/* Connect to SPI manager */
if ((ret = SPI_connect()) < 0)
@ -424,7 +300,7 @@ crosstab(PG_FUNCTION_ARGS)
/*
* The provided SQL query must always return three columns.
*
* 1. rowid the label or identifier for each row in the final
* 1. rowname the label or identifier for each row in the final
* result
* 2. category the label or identifier for each column in the
* final result
@ -433,35 +309,78 @@ crosstab(PG_FUNCTION_ARGS)
if (spi_tupdesc->natts != 3)
elog(ERROR, "crosstab: provided SQL must return 3 columns;"
" a rowid, a category, and a values column");
/*
* Check that return tupdesc is compatible with the one we got
* from ret_relname, at least based on number and type of
* attributes
*/
if (!compatTupleDescs(tupdesc, spi_tupdesc))
elog(ERROR, "crosstab: return and sql tuple descriptions are"
" incompatible");
/* allocate memory for user context */
fctx = (crosstab_fctx *) palloc(sizeof(crosstab_fctx));
/*
* OK, we have data, and it seems to be valid, so save it
* for use across calls
*/
fctx->spi_tuptable = spi_tuptable;
fctx->lastrowid = NULL;
funcctx->user_fctx = fctx;
/* total number of tuples to be returned */
funcctx->max_calls = proc;
}
else
{
/* no qualifying tuples */
funcctx->max_calls = 0;
SPI_finish();
SRF_RETURN_DONE(funcctx);
}
/* back to the original memory context */
MemoryContextSwitchTo(oldcontext);
/* get the typeid that represents our return type */
functypeid = get_func_rettype(funcid);
/* check typtype to see if we have a predetermined return type */
functyptype = get_typtype(functypeid);
if (functyptype == 'c')
{
/* Build a tuple description for a functypeid tuple */
tupdesc = TypeGetTupleDesc(functypeid, NIL);
}
else if (functyptype == 'p' && functypeid == RECORDOID)
{
if (fcinfo->nargs != 2)
elog(ERROR, "Wrong number of arguments specified for function");
else
{
int num_catagories = PG_GETARG_INT32(1);
tupdesc = make_crosstab_tupledesc(spi_tupdesc, num_catagories);
}
}
else if (functyptype == 'b')
elog(ERROR, "Invalid kind of return type specified for function");
else
elog(ERROR, "Unknown kind of return type specified for function");
/*
* Check that return tupdesc is compatible with the one we got
* from ret_relname, at least based on number and type of
* attributes
*/
if (!compatTupleDescs(tupdesc, spi_tupdesc))
elog(ERROR, "crosstab: return and sql tuple descriptions are"
" incompatible");
/* allocate a slot for a tuple with this tupdesc */
slot = TupleDescGetSlot(tupdesc);
/* assign slot to function context */
funcctx->slot = slot;
/*
* Generate attribute metadata needed later to produce tuples from raw
* C strings
*/
attinmeta = TupleDescGetAttInMetadata(tupdesc);
funcctx->attinmeta = attinmeta;
/* allocate memory for user context */
fctx = (crosstab_fctx *) palloc(sizeof(crosstab_fctx));
/*
* Save spi data for use across calls
*/
fctx->spi_tuptable = spi_tuptable;
fctx->lastrowid = NULL;
funcctx->user_fctx = fctx;
/* total number of tuples to be returned */
funcctx->max_calls = proc;
}
/* stuff done on every call of the function */
@ -662,3 +581,51 @@ compatTupleDescs(TupleDesc ret_tupdesc, TupleDesc sql_tupdesc)
/* OK, the two tupdescs are compatible for our purposes */
return true;
}
static TupleDesc
make_crosstab_tupledesc(TupleDesc spi_tupdesc, int num_catagories)
{
Form_pg_attribute sql_attr;
Oid sql_atttypid;
TupleDesc tupdesc;
int natts;
AttrNumber attnum;
char attname[NAMEDATALEN];
int i;
/*
* We need to build a tuple description with one column
* for the rowname, and num_catagories columns for the values.
* Each must be of the same type as the corresponding
* spi result input column.
*/
natts = num_catagories + 1;
tupdesc = CreateTemplateTupleDesc(natts, WITHOUTOID);
/* first the rowname column */
attnum = 1;
sql_attr = spi_tupdesc->attrs[0];
sql_atttypid = sql_attr->atttypid;
strcpy(attname, "rowname");
TupleDescInitEntry(tupdesc, attnum, attname, sql_atttypid,
-1, 0, false);
/* now the catagory values columns */
sql_attr = spi_tupdesc->attrs[2];
sql_atttypid = sql_attr->atttypid;
for (i = 0; i < num_catagories; i++)
{
attnum++;
sprintf(attname, "category_%d", i + 1);
TupleDescInitEntry(tupdesc, attnum, attname, sql_atttypid,
-1, 0, false);
}
return tupdesc;
}

1
contrib/tablefunc/tablefunc.h
View File

@ -32,7 +32,6 @@
/*
* External declarations
*/
extern Datum show_all_settings(PG_FUNCTION_ARGS);
extern Datum normal_rand(PG_FUNCTION_ARGS);
extern Datum crosstab(PG_FUNCTION_ARGS);

12
contrib/tablefunc/tablefunc.sql.in
View File

@ -1,12 +1,3 @@
CREATE VIEW tablefunc_config_settings AS
SELECT
''::TEXT AS name,
''::TEXT AS setting;
CREATE OR REPLACE FUNCTION show_all_settings()
RETURNS setof tablefunc_config_settings
AS 'MODULE_PATHNAME','show_all_settings' LANGUAGE 'c' STABLE STRICT;
CREATE OR REPLACE FUNCTION normal_rand(int4, float8, float8, int4)
RETURNS setof float8
AS 'MODULE_PATHNAME','normal_rand' LANGUAGE 'c' VOLATILE STRICT;
@ -44,3 +35,6 @@ CREATE OR REPLACE FUNCTION crosstab4(text)
RETURNS setof tablefunc_crosstab_4
AS 'MODULE_PATHNAME','crosstab' LANGUAGE 'c' STABLE STRICT;
CREATE OR REPLACE FUNCTION crosstab(text,int)
RETURNS setof record
AS 'MODULE_PATHNAME','crosstab' LANGUAGE 'c' STABLE STRICT;