mirror of https://github.com/citusdata/citus.git
Introduce create_distributed_function(regproc) UDF (#2961)
This PR aims to add the minimal set of changes required to start
distributing functions. You can use create_distributed_function(regproc)
UDF to distribute a function.
SELECT create_distributed_function('add(int,int)');
The function definition should include the param types to properly
identify the correct function that we wish to distribute
pull/2975/head
Hanefi Onaldi
GitHub
parent
012595da11
commit
8f2a3a0604
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@ -0,0 +1,142 @@
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/*-------------------------------------------------------------------------
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*
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* function.c
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* Commands for FUNCTION statements.
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*
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* We currently support replicating function definitions on the
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* coordinator in all the worker nodes in the form of
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*
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* CREATE OR REPLACE FUNCTION ... queries.
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*
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* ALTER or DROP operations are not yet propagated.
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*
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* Copyright (c) 2019, Citus Data, Inc.
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/xact.h"
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#include "catalog/namespace.h"
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#include "catalog/pg_proc.h"
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#include "distributed/metadata_sync.h"
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#include "distributed/metadata/distobject.h"
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#include "distributed/multi_executor.h"
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#include "distributed/relation_access_tracking.h"
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#include "distributed/worker_transaction.h"
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#include "utils/builtins.h"
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#include "utils/fmgrprotos.h"
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/* forward declaration for helper functions*/
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static const char * GetFunctionDDLCommand(Oid funcOid);
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static void EnsureSequentialModeForFunctionDDL(void);
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PG_FUNCTION_INFO_V1(create_distributed_function);
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/*
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* create_distributed_function gets a function or procedure name with their list of
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* argument types in parantheses, then it creates a new distributed function.
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*/
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Datum
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create_distributed_function(PG_FUNCTION_ARGS)
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{
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RegProcedure funcOid = PG_GETARG_OID(0);
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const char *ddlCommand = NULL;
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ObjectAddress functionAddress = { 0 };
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/* if called on NULL input, error out */
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if (funcOid == InvalidOid)
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{
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ereport(ERROR, (errmsg("create_distributed_function() requires a single "
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"parameter that is a valid function or procedure name "
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"followed by a list of parameters in parantheses"),
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errhint("skip the parameters with OUT argtype as they are not "
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"part of the signature in PostgreSQL")));
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}
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ObjectAddressSet(functionAddress, ProcedureRelationId, funcOid);
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/*
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* when we allow propagation within a transaction block we should make sure to only
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* allow this in sequential mode
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*/
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EnsureSequentialModeForFunctionDDL();
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EnsureDependenciesExistsOnAllNodes(&functionAddress);
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ddlCommand = GetFunctionDDLCommand(funcOid);
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SendCommandToWorkers(ALL_WORKERS, ddlCommand);
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MarkObjectDistributed(&functionAddress);
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PG_RETURN_VOID();
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}
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/*
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* GetFunctionDDLCommand returns the complete "CREATE OR REPLACE FUNCTION ..." statement for
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* the specified function.
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*/
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static const char *
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GetFunctionDDLCommand(RegProcedure funcOid)
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{
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OverrideSearchPath *overridePath = NULL;
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Datum sqlTextDatum = 0;
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const char *sql = NULL;
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/*
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* Set search_path to NIL so that all objects outside of pg_catalog will be
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* schema-prefixed. pg_catalog will be added automatically when we call
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* PushOverrideSearchPath(), since we set addCatalog to true;
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*/
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overridePath = GetOverrideSearchPath(CurrentMemoryContext);
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overridePath->schemas = NIL;
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overridePath->addCatalog = true;
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PushOverrideSearchPath(overridePath);
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sqlTextDatum = DirectFunctionCall1(pg_get_functiondef,
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ObjectIdGetDatum(funcOid));
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/* revert back to original search_path */
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PopOverrideSearchPath();
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sql = TextDatumGetCString(sqlTextDatum);
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return sql;
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}
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/*
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* EnsureSequentialModeForFunctionDDL makes sure that the current transaction is already in
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* sequential mode, or can still safely be put in sequential mode, it errors if that is
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* not possible. The error contains information for the user to retry the transaction with
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* sequential mode set from the beginnig.
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*
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* As functions are node scoped objects there exists only 1 instance of the function used by
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* potentially multiple shards. To make sure all shards in the transaction can interact
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* with the function the function needs to be visible on all connections used by the transaction,
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* meaning we can only use 1 connection per node.
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*/
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static void
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EnsureSequentialModeForFunctionDDL(void)
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{
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if (ParallelQueryExecutedInTransaction())
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{
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ereport(ERROR, (errmsg("cannot create function because there was a "
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"parallel operation on a distributed table in the "
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"transaction"),
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errdetail("When creating a distributed function, Citus needs to "
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"perform all operations over a single connection per "
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"node to ensure consistency."),
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errhint("Try re-running the transaction with "
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"\"SET LOCAL citus.multi_shard_modify_mode TO "
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"\'sequential\';\"")));
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}
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ereport(DEBUG1, (errmsg("switching to sequential query execution mode"),
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errdetail(
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"A distributed function is created. To make sure subsequent "
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"commands see the type correctly we need to make sure to "
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"use only one connection for all future commands")));
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SetLocalMultiShardModifyModeToSequential();
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}
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@ -41,6 +41,8 @@ CREATE TABLE citus.pg_dist_object (
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CONSTRAINT pg_dist_object_pkey PRIMARY KEY (classid, objid, objsubid)
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);
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#include "udfs/create_distributed_function/9.0-1.sql"
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#include "udfs/citus_drop_trigger/9.0-1.sql"
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#include "udfs/citus_prepare_pg_upgrade/9.0-1.sql"
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#include "udfs/citus_finish_pg_upgrade/9.0-1.sql"
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@ -0,0 +1,7 @@
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CREATE OR REPLACE FUNCTION create_distributed_function(function_name regprocedure)
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RETURNS void
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LANGUAGE C CALLED ON NULL INPUT
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AS 'MODULE_PATHNAME', $$create_distributed_function$$;
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COMMENT ON FUNCTION create_distributed_function(function_name regprocedure)
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IS 'creates a distributed function';
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@ -0,0 +1,7 @@
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CREATE OR REPLACE FUNCTION create_distributed_function(function_name regprocedure)
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RETURNS void
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LANGUAGE C CALLED ON NULL INPUT
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AS 'MODULE_PATHNAME', $$create_distributed_function$$;
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COMMENT ON FUNCTION create_distributed_function(function_name regprocedure)
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IS 'creates a distributed function';
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@ -0,0 +1,72 @@
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SET citus.next_shard_id TO 20020000;
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CREATE USER functionuser;
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NOTICE: not propagating CREATE ROLE/USER commands to worker nodes
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HINT: Connect to worker nodes directly to manually create all necessary users and roles.
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SELECT run_command_on_workers($$CREATE USER functionuser;$$);
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run_command_on_workers
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-----------------------------------
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(localhost,57637,t,"CREATE ROLE")
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(localhost,57638,t,"CREATE ROLE")
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(2 rows)
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CREATE SCHEMA function_tests AUTHORIZATION functionuser;
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SET search_path TO function_tests;
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SET citus.shard_count TO 4;
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-- Create and distribute a simple function
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CREATE FUNCTION add(integer, integer) RETURNS integer
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AS 'select $1 + $2;'
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LANGUAGE SQL
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IMMUTABLE
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RETURNS NULL ON NULL INPUT;
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SELECT create_distributed_function('add(int,int)');
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create_distributed_function
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-----------------------------
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(1 row)
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SELECT * FROM run_command_on_workers('SELECT function_tests.add(2,3);') ORDER BY 1,2;
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nodename | nodeport | success | result
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-----------+----------+---------+--------
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localhost | 57637 | t | 5
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localhost | 57638 | t | 5
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(2 rows)
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-- Test some combination of functions without ddl propagation
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-- This will prevent the workers from having those types created. They are
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-- created just-in-time on function distribution
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SET citus.enable_ddl_propagation TO off;
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CREATE TYPE dup_result AS (f1 int, f2 text);
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CREATE FUNCTION dup(int) RETURNS dup_result
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AS $$ SELECT $1, CAST($1 AS text) || ' is text' $$
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LANGUAGE SQL;
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SELECT create_distributed_function('dup(int)');
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create_distributed_function
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-----------------------------
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(1 row)
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SELECT * FROM run_command_on_workers('SELECT function_tests.dup(42);') ORDER BY 1,2;
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nodename | nodeport | success | result
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-----------+----------+---------+-------------------
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localhost | 57637 | t | (42,"42 is text")
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localhost | 57638 | t | (42,"42 is text")
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(2 rows)
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-- clear objects
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SET client_min_messages TO fatal; -- suppress cascading objects dropping
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DROP SCHEMA function_tests CASCADE;
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SELECT run_command_on_workers($$DROP SCHEMA function_tests CASCADE;$$);
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run_command_on_workers
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-----------------------------------
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(localhost,57637,t,"DROP SCHEMA")
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(localhost,57638,t,"DROP SCHEMA")
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(2 rows)
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DROP USER functionuser;
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SELECT run_command_on_workers($$DROP USER functionuser;$$);
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run_command_on_workers
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---------------------------------
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(localhost,57637,t,"DROP ROLE")
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(localhost,57638,t,"DROP ROLE")
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(2 rows)
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@ -281,3 +281,4 @@ test: ssl_by_default
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# object distribution tests
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# ---------
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test: distributed_types
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test: distributed_functions
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@ -0,0 +1,41 @@
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SET citus.next_shard_id TO 20020000;
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CREATE USER functionuser;
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SELECT run_command_on_workers($$CREATE USER functionuser;$$);
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CREATE SCHEMA function_tests AUTHORIZATION functionuser;
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SET search_path TO function_tests;
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SET citus.shard_count TO 4;
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-- Create and distribute a simple function
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CREATE FUNCTION add(integer, integer) RETURNS integer
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AS 'select $1 + $2;'
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LANGUAGE SQL
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IMMUTABLE
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RETURNS NULL ON NULL INPUT;
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SELECT create_distributed_function('add(int,int)');
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SELECT * FROM run_command_on_workers('SELECT function_tests.add(2,3);') ORDER BY 1,2;
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-- Test some combination of functions without ddl propagation
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-- This will prevent the workers from having those types created. They are
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-- created just-in-time on function distribution
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SET citus.enable_ddl_propagation TO off;
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CREATE TYPE dup_result AS (f1 int, f2 text);
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CREATE FUNCTION dup(int) RETURNS dup_result
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AS $$ SELECT $1, CAST($1 AS text) || ' is text' $$
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LANGUAGE SQL;
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SELECT create_distributed_function('dup(int)');
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SELECT * FROM run_command_on_workers('SELECT function_tests.dup(42);') ORDER BY 1,2;
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-- clear objects
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SET client_min_messages TO fatal; -- suppress cascading objects dropping
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DROP SCHEMA function_tests CASCADE;
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SELECT run_command_on_workers($$DROP SCHEMA function_tests CASCADE;$$);
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DROP USER functionuser;
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SELECT run_command_on_workers($$DROP USER functionuser;$$);
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