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/* * tablefunc * * Sample to demonstrate C functions which return setof scalar * and setof composite. * Joe Conway <mail@joeconway.com> * * 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: 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. 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. connectby(text relname, text keyid_fld, text parent_keyid_fld, text start_with, int max_depth [, text branch_delim]) - returns keyid, parent_keyid, level, and an optional branch string - requires anonymous composite type syntax in the FROM clause. See the instructions in the documentation below. Documentation ================================================================== 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) ================================================================== 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) ================================================================== Name connectby(text, text, text, text, int[, text]) - returns a set representing a hierarchy (tree structure) Synopsis connectby(text relname, text keyid_fld, text parent_keyid_fld, text start_with, int max_depth [, text branch_delim]) Inputs relname Name of the source relation keyid_fld Name of the key field parent_keyid_fld Name of the key_parent field start_with root value of the tree input as a text value regardless of keyid_fld type max_depth zero (0) for unlimited depth, otherwise restrict level to this depth branch_delim If optional branch value is desired, this string is used as the delimiter. When not provided, a default value of '~' is used for internal recursion detection only, and no "branch" field is returned. Outputs Returns setof record, which must defined with a column definition in the FROM clause of the SELECT statement, e.g.: SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'row2', 0, '~') AS t(keyid text, parent_keyid text, level int, branch text); - or - SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'row2', 0) AS t(keyid text, parent_keyid text, level int); Notes 1. keyid and parent_keyid must be the same data type 2. The column definition *must* include a third column of type INT4 for the level value output 3. If the branch field is not desired, omit both the branch_delim input parameter *and* the branch field in the query column definition. Note that when branch_delim is not provided, a default value of '~' is used for branch_delim for internal recursion detection, even though the branch field is not returned. 4. If the branch field is desired, it must be the fourth column in the query column definition, and it must be type TEXT. 5. The parameters representing table and field names must include double quotes if the names are mixed-case or contain special characters. Example usage CREATE TABLE connectby_tree(keyid text, parent_keyid text); INSERT INTO connectby_tree VALUES('row1',NULL); INSERT INTO connectby_tree VALUES('row2','row1'); INSERT INTO connectby_tree VALUES('row3','row1'); INSERT INTO connectby_tree VALUES('row4','row2'); INSERT INTO connectby_tree VALUES('row5','row2'); INSERT INTO connectby_tree VALUES('row6','row4'); INSERT INTO connectby_tree VALUES('row7','row3'); INSERT INTO connectby_tree VALUES('row8','row6'); INSERT INTO connectby_tree VALUES('row9','row5'); -- with branch SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'row2', 0, '~') AS t(keyid text, parent_keyid text, level int, branch text); keyid | parent_keyid | level | branch -------+--------------+-------+--------------------- row2 | | 0 | row2 row4 | row2 | 1 | row2~row4 row6 | row4 | 2 | row2~row4~row6 row8 | row6 | 3 | row2~row4~row6~row8 row5 | row2 | 1 | row2~row5 row9 | row5 | 2 | row2~row5~row9 (6 rows) -- without branch SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'row2', 0) AS t(keyid text, parent_keyid text, level int); keyid | parent_keyid | level -------+--------------+------- row2 | | 0 row4 | row2 | 1 row6 | row4 | 2 row8 | row6 | 3 row5 | row2 | 1 row9 | row5 | 2 (6 rows) ================================================================== -- Joe Conway