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Copy file name to clipboardExpand all lines: contrib/pg_variables/README.md
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The**pg_variables** module provides functions to work with variables of various
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types. Created variables live only in the current user session.
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Note that the module does**not support transactions and savepoints**. For
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example:
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```sql
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SELECT pgv_set_int('vars','int1',101);
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BEGIN;
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SELECT pgv_set_int('vars','int2',102);
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ROLLBACK;
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SELECT*FROM pgv_list()order by package, name;
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package | name
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---------+------
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vars | int1
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vars | int2
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(2 rows)
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```
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##License
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This module available under the same license as
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##Module functions
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The functions provided by the**pg_variables** module are shown in the tables
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below. The module supports the following scalar and record types.
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To use**pgv_get_()** functions required package and variable must exists. It is
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necessary to set variable with**pgv_set_()** functions to use**pgv_get_()**
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functions.
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If a package does not exists you will get the following error:
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```sql
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SELECT pgv_get_int('vars','int1');
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ERROR: unrecognized package"vars"
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```
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If a variable does not exists you will get the following error:
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```sql
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SELECT pgv_get_int('vars','int1');
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ERROR: unrecognized variable"int1"
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```
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**pgv_get_()** functions check the variable type. If the variable type does not
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match with the function type the error will be raised:
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```sql
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SELECT pgv_get_text('vars','int1');
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ERROR: variable"int1" requires"integer" value
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```
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###Integer variables
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Function | Returns
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###Records
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Function | Returns
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-------- | -------
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`pgv_insert(package text, name text, r record)` |`void`
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`pgv_update(package text, name text, r record)` |`boolean`
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`pgv_delete(package text, name text, value anynonarray)` |`boolean`
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`pgv_select(package text, name text)` |`set of record`
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`pgv_select(package text, name text, value anynonarray)` |`record`
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`pgv_select(package text, name text, value anyarray)` |`set of record`
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The following functions are provided by the module to work with collections of
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record types.
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To use**pgv_update()**,**pgv_delete()** and**pgv_select()** functions
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required package and variable must exists. Otherwise the error will be raised.
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It is necessary to set variable with**pgv_insert()** function to use these
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functions.
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**pgv_update()**,**pgv_delete()** and**pgv_select()** functions check the
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variable type. If the variable type does not**record** type the error will be
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raised.
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Function | Returns | Description
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-------- | ------- | -----------
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`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 of**r** 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.
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`pgv_update(package text, name text, r record)` |`boolean` | Updates a record with the corresponding primary key (the first column of**r** is a primary key). Returns**true** if a record was found. If this variable collection has other structure the error will be raised.
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`pgv_delete(package text, name text, value anynonarray)` |`boolean` | Deletes a record with the corresponding primary key (the first column of**r** is a primary key). Returns**true** if a record was found.
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`pgv_select(package text, name text)` |`set of record` | Returns the variable collection records.
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`pgv_select(package text, name text, value anynonarray)` |`record` | Returns the record with the corresponding primary key (the first column of**r** is a primary key).
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`pgv_select(package text, name text, value anyarray)` |`set of record` | Returns the variable collection records with the corresponding primary keys (the first column of**r** is a primary key).
`pgv_exists(package text, name text)` |`bool` | Returns**true** if package and variable exists.
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`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.
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`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.
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`pgv_free()` |`void` | Removes all packages and variables.
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`pgv_list()` |`table(package text, name text)` | Returns set of records of assigned packages and variables.
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`pgv_stats()` |`table(package text, used_memory bigint)` | Returns list of assigned packages and used memory in bytes.
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Note that**pgv_stats()** works only with the PostgreSQL 9.6 and newer.
