--- /dev/null
+/*
+ * tablefunc
+ *
+ * Sample to demonstrate C functions which return setof scalar
+ * and setof composite.
+ * Joe Conway
+ *
+ * Copyright 2002 by PostgreSQL Global Development Group
+ *
+ * Permission to use, copy, modify, and distribute this software and its
+ * documentation for any purpose, without fee, and without a written agreement
+ * is hereby granted, provided that the above copyright notice and this
+ * paragraph and the following two paragraphs appear in all copies.
+ *
+ * IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
+ * LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
+ * DOCUMENTATION, EVEN IF THE AUTHOR OR DISTRIBUTORS HAVE BEEN ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE AUTHOR AND DISTRIBUTORS HAS NO OBLIGATIONS TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ */
+Version 0.1 (20 July, 2002):
+ First release
+
+Release Notes:
+
+ Version 0.1
+ - initial release
+
+Installation:
+ Place these files in a directory called 'tablefunc' under 'contrib' in the
+ PostgreSQL source tree. Then run:
+
+ make
+ make install
+
+ You can use tablefunc.sql to create the functions in your database of choice, e.g.
+
+ psql -U postgres template1 < tablefunc.sql
+
+ 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
+
+ crosstabN(text sql)
+ - returns a set of row_name plus N category value columns
+ - crosstab2(), crosstab3(), and crosstab4() are defined for you,
+ but you can create additional crosstab functions per 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
+
+Synopsis
+
+normal_rand(int numvals, float8 mean, float8 stddev, int seed)
+
+Inputs
+
+ numvals
+ the number of random values to be returned from the function
+
+ mean
+ the mean of the normal distribution of values
+
+ stddev
+ the standard deviation of the normal distribution of values
+
+ seed
+ a seed value for the pseudo-random number generator
+
+Outputs
+
+ Returns setof float8, where the returned set of random values are normally
+ distributed (Gaussian distribution)
+
+Example usage
+
+ test=# SELECT * FROM
+ test=# normal_rand(1000, 5, 3, EXTRACT(SECONDS FROM CURRENT_TIME(0))::int);
+ normal_rand
+----------------------
+ 1.56556322244898
+ 9.10040991424657
+ 5.36957140345079
+ -0.369151492880995
+ 0.283600703686639
+ .
+ .
+ .
+ 4.82992125404908
+ 9.71308014517282
+ 2.49639286969028
+(1000 rows)
+
+ Returns 1000 values with a mean of 5 and a standard deviation of 3.
+
+==================================================================
+Name
+
+crosstabN(text) - returns a set of row_name plus N category value columns
+
+Synopsis
+
+crosstabN(text sql)
+
+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
+
+Outputs
+
+ Returns setof tablefunc_crosstab_N, which is defined by:
+
+ CREATE VIEW tablefunc_crosstab_N AS
+ SELECT
+ ''::TEXT AS row_name,
+ ''::TEXT AS category_1,
+ ''::TEXT AS category_2,
+ .
+ .
+ .
+ ''::TEXT AS category_N;
+
+ for the default installed functions, where N is 2, 3, or 4.
+
+ e.g. the provided crosstab2 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 depends on the tuple description
+ of the function's declared return type.
+
+ 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.
+
+ 6. The installed defaults are for illustration purposes. You
+ can create your own return types and functions based on the
+ crosstab() function of the installed library.
+
+ The return type must have a first column that matches the data
+ type of the sql set used as its source. The subsequent category
+ columns must have the same data type as the value column of the
+ sql result set.
+
+ Create a VIEW to define your return type, similar to the VIEWS
+ in the provided installation script. Then define a unique function
+ name accepting one text parameter and returning setof your_view_name.
+ For example, if your source data produces row_names that are TEXT,
+ and values that are FLOAT8, and you want 5 category columns:
+
+ CREATE VIEW my_crosstab_float8_5_cols AS
+ SELECT
+ ''::TEXT AS row_name,
+ 0::FLOAT8 AS category_1,
+ 0::FLOAT8 AS category_2,
+ 0::FLOAT8 AS category_3,
+ 0::FLOAT8 AS category_4,
+ 0::FLOAT8 AS category_5;
+
+ CREATE OR REPLACE FUNCTION crosstab_float8_5_cols(text)
+ RETURNS setof my_crosstab_float8_5_cols
+ AS '$libdir/tablefunc','crosstab' LANGUAGE 'c' STABLE STRICT;
+
+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 crosstab3(
+ 'select rowid, attribute, value
+ from ct
+ where rowclass = ''group1''
+ and (attribute = ''att2'' or attribute = ''att3'') order by 1,2;');
+
+ row_name | category_1 | category_2 | category_3
+----------+------------+------------+------------
+ test1 | val2 | val3 |
+ test2 | val6 | val7 |
+(2 rows)
+
+==================================================================
+-- Joe Conway
+
--- /dev/null
+--
+-- show_all_settings()
+--
+SELECT * FROM show_all_settings();
+
+--
+-- normal_rand()
+--
+SELECT * FROM normal_rand(100, 250, 5, EXTRACT(SECONDS FROM CURRENT_TIME(0))::int);
+
+--
+-- crosstab()
+--
+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');
+insert into ct(rowclass, rowid, attribute, value) values('group2','test3','att1','val1');
+insert into ct(rowclass, rowid, attribute, value) values('group2','test3','att2','val2');
+insert into ct(rowclass, rowid, attribute, value) values('group2','test3','att3','val3');
+insert into ct(rowclass, rowid, attribute, value) values('group2','test4','att1','val4');
+insert into ct(rowclass, rowid, attribute, value) values('group2','test4','att2','val5');
+insert into ct(rowclass, rowid, attribute, value) values('group2','test4','att3','val6');
+
+select * from crosstab2('select rowid, attribute, value from ct where rowclass = ''group1'' and (attribute = ''att2'' or attribute = ''att3'') order by 1,2;');
+select * from crosstab3('select rowid, attribute, value from ct where rowclass = ''group1'' and (attribute = ''att2'' or attribute = ''att3'') order by 1,2;');
+select * from crosstab4('select rowid, attribute, value from ct where rowclass = ''group1'' and (attribute = ''att2'' or attribute = ''att3'') order by 1,2;');
+
+select * from crosstab2('select rowid, attribute, value from ct where rowclass = ''group1'' order by 1,2;');
+select * from crosstab3('select rowid, attribute, value from ct where rowclass = ''group1'' order by 1,2;');
+select * from crosstab4('select rowid, attribute, value from ct where rowclass = ''group1'' order by 1,2;');
+
+select * from crosstab2('select rowid, attribute, value from ct where rowclass = ''group2'' and (attribute = ''att1'' or attribute = ''att2'') order by 1,2;');
+select * from crosstab3('select rowid, attribute, value from ct where rowclass = ''group2'' and (attribute = ''att1'' or attribute = ''att2'') order by 1,2;');
+select * from crosstab4('select rowid, attribute, value from ct where rowclass = ''group2'' and (attribute = ''att1'' or attribute = ''att2'') order by 1,2;');
+
+select * from crosstab2('select rowid, attribute, value from ct where rowclass = ''group2'' order by 1,2;');
+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;');
+
+
--- /dev/null
+/*
+ * tablefunc
+ *
+ * Sample to demonstrate C functions which return setof scalar
+ * and setof composite.
+ * Joe Conway
+ *
+ * Copyright 2002 by PostgreSQL Global Development Group
+ *
+ * Permission to use, copy, modify, and distribute this software and its
+ * documentation for any purpose, without fee, and without a written agreement
+ * is hereby granted, provided that the above copyright notice and this
+ * paragraph and the following two paragraphs appear in all copies.
+ *
+ * IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
+ * LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
+ * DOCUMENTATION, EVEN IF THE AUTHOR OR DISTRIBUTORS HAVE BEEN ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE AUTHOR AND DISTRIBUTORS HAS NO OBLIGATIONS TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ */
+#include
+#include
+
+#include "postgres.h"
+
+#include "fmgr.h"
+#include "funcapi.h"
+#include "executor/spi.h"
+#include "utils/builtins.h"
+#include "utils/guc.h"
+
+#include "tablefunc.h"
+
+static bool compatTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2);
+static void get_normal_pair(float8 *x1, float8 *x2);
+
+typedef struct
+{
+ float8 mean; /* mean of the distribution */
+ float8 stddev; /* stddev of the distribution */
+ float8 carry_val; /* hold second generated value */
+ bool use_carry; /* use second generated value */
+} normal_rand_fctx;
+
+typedef struct
+{
+ SPITupleTable *spi_tuptable; /* sql results from user query */
+ char *lastrowid; /* rowid of the last tuple sent */
+} crosstab_fctx;
+
+#define GET_TEXT(cstrp) DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum(cstrp)))
+#define GET_STR(textp) DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(textp)))
+#define xpfree(var_) \
+ do { \
+ if (var_ != NULL) \
+ { \
+ pfree(var_); \
+ var_ = NULL; \
+ } \
+ } 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.
+ *
+ * inputs are int numvals, float8 lower_bound, and float8 upper_bound
+ * returns float8
+ */
+PG_FUNCTION_INFO_V1(normal_rand);
+Datum
+normal_rand(PG_FUNCTION_ARGS)
+{
+ FuncCallContext *funcctx;
+ int call_cntr;
+ int max_calls;
+ normal_rand_fctx *fctx;
+ float8 mean;
+ float8 stddev;
+ float8 carry_val;
+ bool use_carry;
+
+ /* stuff done only on the first call of the function */
+ if(SRF_IS_FIRSTCALL())
+ {
+ /* create a function context for cross-call persistence */
+ funcctx = SRF_FIRSTCALL_INIT();
+
+ /* total number of tuples to be returned */
+ funcctx->max_calls = PG_GETARG_UINT32(0);
+
+ /* allocate memory for user context */
+ fctx = (normal_rand_fctx *) palloc(sizeof(normal_rand_fctx));
+
+ /*
+ * Use fctx to keep track of upper and lower bounds
+ * from call to call. It will also be used to carry over
+ * the spare value we get from the Box-Muller algorithm
+ * so that we only actually calculate a new value every
+ * other call.
+ */
+ fctx->mean = PG_GETARG_FLOAT8(1);
+ fctx->stddev = PG_GETARG_FLOAT8(2);
+ fctx->carry_val = 0;
+ fctx->use_carry = false;
+
+ funcctx->user_fctx = fctx;
+
+ /*
+ * we might actually get passed a negative number, but for this
+ * purpose it doesn't matter, just cast it as an unsigned value
+ */
+ srandom(PG_GETARG_UINT32(3));
+ }
+
+ /* stuff done on every call of the function */
+ funcctx = SRF_PERCALL_SETUP();
+
+ call_cntr = funcctx->call_cntr;
+ max_calls = funcctx->max_calls;
+ fctx = funcctx->user_fctx;
+ mean = fctx->mean;
+ stddev = fctx->stddev;
+ carry_val = fctx->carry_val;
+ use_carry = fctx->use_carry;
+
+ if (call_cntr < max_calls) /* do when there is more left to send */
+ {
+ float8 result;
+
+ if(use_carry)
+ {
+ /*
+ * reset use_carry and use second value obtained on last pass
+ */
+ fctx->use_carry = false;
+ result = carry_val;
+ }
+ else
+ {
+ float8 normval_1;
+ float8 normval_2;
+
+ /* Get the next two normal values */
+ get_normal_pair(&normval_1, &normval_2);
+
+ /* use the first */
+ result = mean + (stddev * normval_1);
+
+ /* and save the second */
+ fctx->carry_val = mean + (stddev * normval_2);
+ fctx->use_carry = true;
+ }
+
+ /* send the result */
+ SRF_RETURN_NEXT(funcctx, Float8GetDatum(result));
+ }
+ else /* do when there is no more left */
+ {
+ SRF_RETURN_DONE(funcctx);
+ }
+}
+
+/*
+ * get_normal_pair()
+ * Assigns normally distributed (Gaussian) values to a pair of provided
+ * parameters, with mean 0, standard deviation 1.
+ *
+ * This routine implements Algorithm P (Polar method for normal deviates)
+ * from Knuth's _The_Art_of_Computer_Programming_, Volume 2, 3rd ed., pages
+ * 122-126. Knuth cites his source as "The polar method", G. E. P. Box, M. E.
+ * Muller, and G. Marsaglia, _Annals_Math,_Stat._ 29 (1958), 610-611.
+ *
+ */
+static void
+get_normal_pair(float8 *x1, float8 *x2)
+{
+ float8 u1, u2, v1, v2, s;
+
+ for(;;)
+ {
+ u1 = (float8) random() / (float8) RAND_MAX;
+ u2 = (float8) random() / (float8) RAND_MAX;
+
+ v1 = (2.0 * u1) - 1.0;
+ v2 = (2.0 * u2) - 1.0;
+
+ s = pow(v1, 2) + pow(v2, 2);
+
+ if (s >= 1.0)
+ continue;
+
+ if (s == 0)
+ {
+ *x1 = 0;
+ *x2 = 0;
+ }
+ else
+ {
+ *x1 = v1 * sqrt((-2.0 * log(s)) / s);
+ *x2 = v2 * sqrt((-2.0 * log(s)) / s);
+ }
+
+ return;
+ }
+}
+
+/*
+ * crosstab - create a crosstab of rowids and values columns from a
+ * SQL statement returning one rowid column, one category column,
+ * and one value column.
+ *
+ * e.g. given sql which produces:
+ *
+ * rowid 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
+ *
+ * crosstab returns:
+ * <===== values columns =====>
+ * rowid cat1 cat2 cat3 cat4
+ * ------+-------+-------+-------+-------
+ * row1 val1 val2 val3 val4
+ * row2 val5 val6 val7 val8
+ *
+ * NOTES:
+ * 1. SQL result must be ordered by 1,2.
+ * 2. The number of values columns depends on the tuple description
+ * of the function's declared return type.
+ * 2. Missing values (i.e. not enough adjacent rows of same rowid to
+ * fill the number of result values columns) are filled in with nulls.
+ * 3. Extra values (i.e. too many adjacent rows of same rowid to fill
+ * the number of result values columns) are skipped.
+ * 4. Rows with all nulls in the values columns are skipped.
+ */
+PG_FUNCTION_INFO_V1(crosstab);
+Datum
+crosstab(PG_FUNCTION_ARGS)
+{
+ FuncCallContext *funcctx;
+ TupleDesc ret_tupdesc;
+ int call_cntr;
+ int max_calls;
+ TupleTableSlot *slot;
+ AttInMetadata *attinmeta;
+ SPITupleTable *spi_tuptable;
+ TupleDesc spi_tupdesc;
+ char *lastrowid;
+ crosstab_fctx *fctx;
+ int i;
+ int num_categories;
+
+ /* 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;
+
+ /* 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;
+
+ /* Connect to SPI manager */
+ if ((ret = SPI_connect()) < 0)
+ elog(ERROR, "crosstab: SPI_connect returned %d", ret);
+
+ /* Retrieve the desired rows */
+ ret = SPI_exec(sql, 0);
+ proc = SPI_processed;
+
+ /* Check for qualifying tuples */
+ if ((ret == SPI_OK_SELECT) && (proc > 0))
+ {
+ spi_tuptable = SPI_tuptable;
+ spi_tupdesc = spi_tuptable->tupdesc;
+
+ /*
+ * The provided SQL query must always return three columns.
+ *
+ * 1. rowid the label or identifier for each row in the final
+ * result
+ * 2. category the label or identifier for each column in the
+ * final result
+ * 3. values the value for each column in the final result
+ */
+ 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;
+ }
+ }
+
+ /* stuff done on every call of the function */
+ funcctx = SRF_PERCALL_SETUP();
+
+ /*
+ * initialize per-call variables
+ */
+ call_cntr = funcctx->call_cntr;
+ max_calls = funcctx->max_calls;
+
+ /* return slot for our tuple */
+ slot = funcctx->slot;
+
+ /* user context info */
+ fctx = (crosstab_fctx *) funcctx->user_fctx;
+ lastrowid = fctx->lastrowid;
+ spi_tuptable = fctx->spi_tuptable;
+
+ /* the sql tuple */
+ spi_tupdesc = spi_tuptable->tupdesc;
+
+ /* attribute return type and return tuple description */
+ attinmeta = funcctx->attinmeta;
+ ret_tupdesc = attinmeta->tupdesc;
+
+ /* the return tuple always must have 1 rowid + num_categories columns */
+ num_categories = ret_tupdesc->natts - 1;
+
+ if (call_cntr < max_calls) /* do when there is more left to send */
+ {
+ HeapTuple tuple;
+ Datum result;
+ char **values;
+ bool allnulls = true;
+
+ while (true)
+ {
+ /* allocate space */
+ values = (char **) palloc((1 + num_categories) * sizeof(char *));
+
+ /* and make sure it's clear */
+ memset(values, '\0', (1 + num_categories) * sizeof(char *));
+
+ /*
+ * now loop through the sql results and assign each value
+ * in sequence to the next category
+ */
+ for (i = 0; i < num_categories; i++)
+ {
+ HeapTuple spi_tuple;
+ char *rowid;
+
+ /* see if we've gone too far already */
+ if (call_cntr >= max_calls)
+ break;
+
+ /* get the next sql result tuple */
+ spi_tuple = spi_tuptable->vals[call_cntr];
+
+ /* get the rowid from the current sql result tuple */
+ rowid = SPI_getvalue(spi_tuple, spi_tupdesc, 1);
+
+ /*
+ * If this is the first pass through the values for this rowid
+ * set it, otherwise make sure it hasn't changed on us. Also
+ * check to see if the rowid is the same as that of the last
+ * tuple sent -- if so, skip this tuple entirely
+ */
+ if (i == 0)
+ values[0] = pstrdup(rowid);
+
+ if ((rowid != NULL) && (strcmp(rowid, values[0]) == 0))
+ {
+ if ((lastrowid != NULL) && (strcmp(rowid, lastrowid) == 0))
+ break;
+ else if (allnulls == true)
+ allnulls = false;
+
+ /*
+ * Get the next category item value, which is alway attribute
+ * number three.
+ *
+ * Be careful to sssign the value to the array index based
+ * on which category we are presently processing.
+ */
+ values[1 + i] = SPI_getvalue(spi_tuple, spi_tupdesc, 3);
+
+ /*
+ * increment the counter since we consume a row
+ * for each category, but not for last pass
+ * because the API will do that for us
+ */
+ if (i < (num_categories - 1))
+ call_cntr = ++funcctx->call_cntr;
+ }
+ else
+ {
+ /*
+ * We'll fill in NULLs for the missing values,
+ * but we need to decrement the counter since
+ * this sql result row doesn't belong to the current
+ * output tuple.
+ */
+ call_cntr = --funcctx->call_cntr;
+ break;
+ }
+
+ if (rowid != NULL)
+ xpfree(rowid);
+ }
+
+ xpfree(fctx->lastrowid);
+
+ if (values[0] != NULL)
+ lastrowid = fctx->lastrowid = pstrdup(values[0]);
+
+ if (!allnulls)
+ {
+ /* build the tuple */
+ tuple = BuildTupleFromCStrings(attinmeta, values);
+
+ /* make the tuple into a datum */
+ result = TupleGetDatum(slot, tuple);
+
+ /* Clean up */
+ for (i = 0; i < num_categories + 1; i++)
+ if (values[i] != NULL)
+ xpfree(values[i]);
+ xpfree(values);
+
+ SRF_RETURN_NEXT(funcctx, result);
+ }
+ else
+ {
+ /*
+ * Skipping this tuple entirely, but we need to advance
+ * the counter like the API would if we had returned
+ * one.
+ */
+ call_cntr = ++funcctx->call_cntr;
+
+ /* we'll start over at the top */
+ xpfree(values);
+
+ /* see if we've gone too far already */
+ if (call_cntr >= max_calls)
+ {
+ /* release SPI related resources */
+ SPI_finish();
+ SRF_RETURN_DONE(funcctx);
+ }
+ }
+ }
+ }
+ else /* do when there is no more left */
+ {
+ /* release SPI related resources */
+ SPI_finish();
+ SRF_RETURN_DONE(funcctx);
+ }
+}
+
+/*
+ * Check if two tupdescs match in type of attributes
+ */
+static bool
+compatTupleDescs(TupleDesc ret_tupdesc, TupleDesc sql_tupdesc)
+{
+ int i;
+ Form_pg_attribute ret_attr;
+ Oid ret_atttypid;
+ Form_pg_attribute sql_attr;
+ Oid sql_atttypid;
+
+ /* check the rowid types match */
+ ret_atttypid = ret_tupdesc->attrs[0]->atttypid;
+ sql_atttypid = sql_tupdesc->attrs[0]->atttypid;
+ if (ret_atttypid != sql_atttypid)
+ elog(ERROR, "compatTupleDescs: SQL rowid datatype does not match"
+ " return rowid datatype");
+
+ /*
+ * - attribute [1] of the sql tuple is the category;
+ * no need to check it
+ * - attribute [2] of the sql tuple should match
+ * attributes [1] to [natts] of the return tuple
+ */
+ sql_attr = sql_tupdesc->attrs[2];
+ for (i = 1; i < ret_tupdesc->natts; i++)
+ {
+ ret_attr = ret_tupdesc->attrs[i];
+
+ if (ret_attr->atttypid != sql_attr->atttypid)
+ return false;
+ }
+
+ /* OK, the two tupdescs are compatible for our purposes */
+ return true;
+}
projects / postgresql.git / commitdiff