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Session wide variables for PostgreSQL

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README.md		README.md
pg_variables--1.0.sql		pg_variables--1.0.sql
pg_variables.c		pg_variables.c
pg_variables.control		pg_variables.control
pg_variables.h		pg_variables.h
pg_variables_record.c		pg_variables_record.c

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pg_variables - session variables with various types

Introduction

Thepg_variables module provides functions to work with variables of varioustypes. Created variables live only in the current user session.

Note that the module doesnot support transactions and savepoints. Forexample:

SELECT pgv_set('vars','int1',101);BEGIN;SELECT pgv_set('vars','int2',102);ROLLBACK;SELECT*FROM pgv_list()order by package, name; package | name---------+------ vars    | int1 vars    | int2(2 rows)

License

This module available under the same license asPostgreSQL.

Installation

Typical installation procedure may look like this:

$ cd pg_variables$ make USE_PGXS=1$ sudo make USE_PGXS=1 install$ make USE_PGXS=1 installcheck$ psql DB -c "CREATE EXTENSION pg_variables;"

Module functions

The functions provided by thepg_variables module are shown in the tablesbelow. The module supports the following scalar and record types.

To usepgv_get() function required package and variable must exists. It isnecessary to set variable withpgv_set() function to usepgv_get()function.

If a package does not exists you will get the following error:

SELECT pgv_get('vars','int1',NULL::int);ERROR:  unrecognized package"vars"

If a variable does not exists you will get the following error:

SELECT pgv_get('vars','int1',NULL::int);ERROR:  unrecognized variable"int1"

pgv_get() function check the variable type. If the variable type does notmatch with the function type the error will be raised:

SELECT pgv_get('vars','int1',NULL::text);ERROR:  variable"int1" requires"integer" value

Scalar variables functions

Function	Returns
`pgv_set(package text, name text, value anynonarray)`	`void`
`pgv_get(package text, name text, var_type anynonarray, strict bool default true)`	`anynonarray`

Deprecated scalar variables functions

Integer variables

Function	Returns
`pgv_set_int(package text, name text, value int)`	`void`
`pgv_get_int(package text, name text, strict bool default true)`	`int`

Text variables

Function	Returns
`pgv_set_text(package text, name text, value text)`	`void`
`pgv_get_text(package text, name text, strict bool default true)`	`text`

Numeric variables

Function	Returns
`pgv_set_numeric(package text, name text, value numeric)`	`void`
`pgv_get_numeric(package text, name text, strict bool default true)`	`numeric`

Timestamp variables

Function	Returns
`pgv_set_timestamp(package text, name text, value timestamp)`	`void`
`pgv_get_timestamp(package text, name text, strict bool default true)`	`timestamp`

Timestamp with timezone variables

Function	Returns
`pgv_set_timestamptz(package text, name text, value timestamptz)`	`void`
`pgv_get_timestamptz(package text, name text, strict bool default true)`	`timestamptz`

Date variables

Function	Returns
`pgv_set_date(package text, name text, value date)`	`void`
`pgv_get_date(package text, name text, strict bool default true)`	`date`

Jsonb variables

Function	Returns
`pgv_set_jsonb(package text, name text, value jsonb)`	`void`
`pgv_get_jsonb(package text, name text, strict bool default true)`	`jsonb`

Record variables functions

The following functions are provided by the module to work with collections ofrecord types.

To usepgv_update(),pgv_delete() andpgv_select() functionsrequired package and variable must exists. Otherwise the error will be raised.It is necessary to set variable withpgv_insert() function to use thesefunctions.

pgv_update(),pgv_delete() andpgv_select() functions check thevariable type. If the variable type does notrecord type the error will beraised.

Function	Returns	Description
`pgv_insert(package text, name text, r record)`	`void`	Inserts a record to the variable collection. If package and variable do not exists they will be created. The first column ofr will be a primary key. If exists a record with the same primary key the error will be raised. If this variable collection has other structure the error will be raised.
`pgv_update(package text, name text, r record)`	`boolean`	Updates a record with the corresponding primary key (the first column ofr is a primary key). Returnstrue if a record was found. If this variable collection has other structure the error will be raised.
`pgv_delete(package text, name text, value anynonarray)`	`boolean`	Deletes a record with the corresponding primary key (the first column ofr is a primary key). Returnstrue if a record was found.
`pgv_select(package text, name text)`	`set of record`	Returns the variable collection records.
`pgv_select(package text, name text, value anynonarray)`	`record`	Returns the record with the corresponding primary key (the first column ofr is a primary key).
`pgv_select(package text, name text, value anyarray)`	`set of record`	Returns the variable collection records with the corresponding primary keys (the first column ofr is a primary key).

Miscellaneous functions

Function	Returns	Description
`pgv_exists(package text, name text)`	`bool`	Returnstrue if package and variable exists.
`pgv_exists(package text)`	`bool`	Returnstrue if package exists.
`pgv_remove(package text, name text)`	`void`	Removes the variable with the corresponding name. Required package and variable must exists, otherwise the error will be raised.
`pgv_remove(package text)`	`void`	Removes the package and all package variables with the corresponding name. Required package must exists, otherwise the error will be raised.
`pgv_free()`	`void`	Removes all packages and variables.
`pgv_list()`	`table(package text, name text)`	Returns set of records of assigned packages and variables.
`pgv_stats()`	`table(package text, used_memory bigint)`	Returns list of assigned packages and used memory in bytes.

Note thatpgv_stats() works only with the PostgreSQL 9.6 and newer.

Examples

It is easy to use functions to work with scalar variables:

SELECT pgv_set('vars','int1',101);SELECT pgv_set('vars','int2',102);SELECT pgv_get('vars','int1',NULL::int); pgv_get_int-------------101(1 row)SELECT pgv_get('vars','int2',NULL::int); pgv_get_int-------------102(1 row)

Let's assume we have atab table:

CREATETABLEtab (idint, tvarchar);INSERT INTO tabVALUES (0,'str00'), (1,'str11');

Then you can use functions to work with record variables:

SELECT pgv_insert('vars','r1', tab)FROM tab;SELECT pgv_select('vars','r1'); pgv_select------------ (1,str11) (0,str00)(2 rows)SELECT pgv_select('vars','r1',1); pgv_select------------ (1,str11)(1 row)SELECT pgv_select('vars','r1',0); pgv_select------------ (0,str00)(1 row)SELECT pgv_select('vars','r1', ARRAY[1,0]); pgv_select------------ (1,str11) (0,str00)(2 rows)SELECT pgv_delete('vars','r1',1);SELECT pgv_select('vars','r1'); pgv_select------------ (0,str00)(1 row)

You can list packages and variables:

SELECT*FROM pgv_list()order by package, name; package | name---------+------ vars    | int1 vars    | int2 vars    | r1(3 rows)

And get used memory in bytes:

SELECT*FROM pgv_stats()order by package; package | used_memory---------+------------- vars    |16736(1 row)

You can delete variables or hole packages:

SELECT pgv_remove('vars','int1');SELECT pgv_remove('vars');

You can delete all packages and variables:

SELECT pgv_free();

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Session wide variables for PostgreSQL

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pg_variables - session variables with various types

Introduction

License

Installation

Module functions

Scalar variables functions

Deprecated scalar variables functions

Integer variables

Text variables

Numeric variables

Timestamp variables

Timestamp with timezone variables

Date variables

Jsonb variables

Record variables functions

Miscellaneous functions

Examples

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