Tableau Server Workgroup PostgreSQL Database Schema And Data Synchronization

Last client who engaged me to architect and develop a small data warehouse for them also made a large investment in Tableau as their default reporting platform. The warehouse data, small by today’s standards, was to be uploaded into Tableau server as a scheduled overnight extract and users granted access to reports/data on Tableau server rather than querying star schema relational tables directly (implemented on the SQL Server database engine). As data availability and therefore meeting BI SLAs was paramount to the project success, a robust notification system was put in place to log any data warehouse issues that may have arisen from all activities on the database server. However, even though all precautions were taken to ensure data warehouse failed processes were logged and corresponding issues mitigated accordingly, Tableau extract failures along with other Tableau server activities were largely unaccounted for due to the lack of data. How could one address this issue?

Tableau provides access to their internal server PostgreSQL metadata database with just a few simple steps. As it turns out, during installation Tableau Server will create the almost empty ‘workgroup’ repository with over 100+ tables, 900+ columns (about 100 of them used as Keys), 300+ joins and 16+ views which can be accessed and queried. Tableau Server works as a collection processes, processors, programs and applications, like data engine, data server, VizQL Server, application server etc. Each of those processes generates log with data about user activities, data connections, queries and extractions, errors, views and interactions, etc. which is parsed regularly and stored into PostgreSQL-based Tableau Server Administrative Database. PostgreSQL Server containing Workgroup DB usually runs on the same Windows Server as Main Tableau Server or (if Tableau Server runs on multi-mode cluster with Worker Tableau Server(s)) on other Windows Server, which runs Worker Tableau Server and uses non-standard TCP/IP port 8060. Tableau’s PostgreSQL database access is provided by means of using a few different accounts, each with its own set of privileges. In November 2014 Tableau Software introduced (Release 8.2.5) a new, default user, named ‘readonly’ with read access to all tables and views of Workgroup Repository which is what I’m going to be using to get ‘under the hood’. Other user commonly used for Tableau server metadata exploration, aptly named ‘tableau’ can also be used for Tableau server activity analysis but has access to fewer database objects.

The easiest way to connect to Tableau’s ‘workgroup’ database using ‘readonly’ account is opening an administrator command prompt on your Tableau Server, navigating to your Tableau Server bin directory and issuing the tabadmin dbpass command, specifying your chosen password. After server restart the changes should take effect and you should be able to see the following output.

Tableau_Workgroup_DB_Sync_Enable_DB_Access

PostgreSQL can now be queried using a client tool of your choice e.g. PgAdmin. This is what the ‘public’ schema with all its tables looks like when imported in Navicat Data Modeller (click on image to enlarge).

Tableau_Workgroup_DB_Sync_DB_ERD_v9point1

In order to connect to it from SQL Server we can simply download PostgreSQL ODBC driver and configure it with the credentials of the ‘readonly’ user.

Tableau_Workgroup_DB_Sync_ODBC_Setup

All there is left to do is to create a linked server connection to PostgreSQL database directly from SQL Server Management Studio, exposing a collection of objects (tables and views) on the public schema.

Tableau_Workgroup_DB_Sync_MSSQL_LinkedSvr_Schema_View

Now we should be able to OPENQUERY Tableau metadata objects with ease but if we would like to go further and regularly copy Tableau’s data across to SQL Server (in case of my client that was precisely the requirement in order not to interfere with production database), the following code should provide this functionality.

Firstly, let’s create a sample database called ‘TableauDBCopy’ and a ‘tab’ schema on the SQL Server target instance. The below SQL snippet also creates and populates a small table called ‘tabSchemaObjectsExclude’ on the ‘dbo’ schema which stores table names we don’t want to import. The reason for this exclusion is that these tables do not contain the primary keys, therefore it is impossible to compare the two schemas using the code below which relies on primary key being defined on every single table object.

--CREATE 'TableauDBCopy' DATABASE AND 'tab' SCHEMA ON THE TARGET INSTANCE/SERVER
USE [master];
GO
IF EXISTS ( SELECT  name
            FROM    sys.databases
            WHERE   name = N'TableauDBCopy' )
    BEGIN
        ALTER DATABASE TableauDBCopy SET SINGLE_USER WITH ROLLBACK IMMEDIATE;
        DROP DATABASE TableauDBCopy;
    END;
GO
CREATE DATABASE TableauDBCopy ON 
( NAME = 'TableauDBCopy_dat',
   FILENAME = 'D:\SQLData\MSSQL12.ServerName\MSSQL\DATA\TableauDBCopy.mdf',
   SIZE = 500MB,
   MAXSIZE = 2000MB,
   FILEGROWTH = 100 ) LOG ON
( NAME = 'TableauDBCopy_log',
   FILENAME = 'D:\SQLData\MSSQL12.ServerName\MSSQL\DATA\TableauDBCopy.ldf',
   SIZE = 100MB,
   MAXSIZE = 1000MB,
   FILEGROWTH = 50MB );
GO
EXEC TableauDBCopy.dbo.sp_changedbowner @loginame = N'SA', @map = false;
GO
ALTER DATABASE TableauDBCopy SET RECOVERY SIMPLE;
GO
USE TableauDBCopy;
GO
CREATE SCHEMA tab AUTHORIZATION dbo;
GO

--CREATE EXCEPTION 'tabSchemaObjectsExclude' TABLE AND POPULATE IT WITH EXCEPTION DATA
CREATE TABLE dbo.tabSchemaObjectsExclude
(ObjectName VARCHAR (256))
GO
INSERT INTO dbo.tabSchemaObjectsExclude( ObjectName )
SELECT 'dataengine_configurations'						UNION ALL
SELECT 'exportable_repository_id_columns'				UNION ALL
SELECT 'exportable_tables_column_transformations'		UNION ALL
SELECT 'monitoring_dataengine'							UNION ALL
SELECT 'monitoring_postgresql'							UNION ALL
SELECT 'permission_reasons'								UNION ALL
SELECT 'schema_migrations'								UNION ALL
SELECT 'users_view'

Next, let’s look at a simple stored procedure which compares the source schema (Tableau server public schema on the PostgreSQL database) with the target schema (our newly created SQL Server database with the ‘tab’ schema). This code is used to interrogate both databases for their ‘compatibility’ and tables metadata structure e.g. data types, character lengths, NULL-ablity, precision, scale etc. and if the target object(s) are found to be missing or out of sync with the source version, it creates a DROP and a CREATE table SQL DDLs statement on the fly and applies the changes directly in the target environment.

USE [TableauDBCopy]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE PROCEDURE [dbo].[usp_checkRemoteTableauServerTablesSchemaChanges]
    (
	  @Remote_Server_Name				VARCHAR			(256),
	  @Remote_Server_DB_Name			VARCHAR			(128),
	  @Remote_Server_DB_Schema_Name		VARCHAR			(128),
	  @Target_DB_Name					VARCHAR			(128),
	  @Target_DB_Schema_Name			VARCHAR			(128),
      @Is_All_OK						INT							OUTPUT ,
      @Process_Name						VARCHAR			(250)		OUTPUT ,
      @Error_Message					VARCHAR			(MAX)		OUTPUT
    )
    WITH RECOMPILE
AS
    SET NOCOUNT ON
    BEGIN
        DECLARE @Is_ReCheck BIT = 0
		DECLARE @SQL NVARCHAR (MAX)
        DECLARE @Is_Debug_Mode BIT = 1
		DECLARE @Remote_Server_Tableau	VARCHAR(55)		= 'TABPOSTGRESQLPROD'
        SET @Process_Name = ( SELECT    OBJECT_NAME(objectid)
                              FROM      sys.dm_exec_requests r
                                        CROSS   APPLY sys.dm_exec_sql_text(r.sql_handle) a
                              WHERE     session_id = @@spid
                            )
		
		IF OBJECT_ID('tempdb..#t_seqfloats') IS NOT NULL
            BEGIN
                DROP TABLE #t_seqfloats			
            END

		;WITH    Nbrs_3 ( n )
          AS ( SELECT   1
               UNION
               SELECT   0
             ),
        Nbrs_2 ( n )
          AS ( SELECT   1
               FROM     Nbrs_3 n1
                        CROSS JOIN Nbrs_3 n2
             ),
        Nbrs_1 ( n )
          AS ( SELECT   1
               FROM     Nbrs_2 n1
                        CROSS JOIN Nbrs_2 n2
             ),
        Nbrs_0 ( n )
          AS ( SELECT   1
               FROM     Nbrs_1 n1
                        CROSS JOIN Nbrs_1 n2
             ),
        Nbrs ( n )
          AS ( SELECT   1
               FROM     Nbrs_0 n1
                        CROSS JOIN Nbrs_0 n2
             )

			 SELECT    'float' + CAST(n AS VARCHAR(2)) seq_floats 
			 INTO #t_seqfloats
                              FROM      ( SELECT    ROW_NUMBER() OVER ( ORDER BY n )
                                          FROM      Nbrs
                                        ) D ( n )
                              WHERE     n <= 53
			UNION ALL 
			SELECT 'float'

        Check_RemoteSvr_Schema:
        IF OBJECT_ID('tempdb..#t_allTblMetadata') IS NOT NULL
            BEGIN
                DROP TABLE [#t_allTblMetadata]			
            END  
		CREATE TABLE tempdb..[#t_allTblMetadata]
		(
		table_name VARCHAR(256),
		column_name VARCHAR(256),
		ordinal_position INT ,
		is_nullable BIT ,
		data_type VARCHAR (256) ,
		character_maximum_length BIGINT,
		numeric_scale SMALLINT,
		numeric_precision SMALLINT,
		is_primary_key BIT,
		local_schema_name VARCHAR(55),
		remote_schema_name VARCHAR(55),
		local_or_remote VARCHAR(25) 
		)
	  
        SET @SQL = '
			INSERT INTO #t_allTblMetadata
				(
					[table_name]
					,[column_name]
					,[ordinal_position]
					,[is_nullable]
					,[data_type]
					,[character_maximum_length]
					,[numeric_scale]
					,[numeric_precision]
					,[is_primary_key]
					,[local_schema_name]
					,[remote_schema_name]
					,[local_or_remote]
				)
			SELECT 
			LTRIM(RTRIM(a.table_name))						AS table_name,
			LTRIM(RTRIM(a.column_name))						AS column_name, 
			LTRIM(RTRIM(a.ordinal_position))				AS ordinal_position,
			CASE WHEN a.is_nullable = ''YES''
			THEN 1 ELSE 0 END 								AS is_nullable,
			LTRIM(RTRIM(a.udt_name))						AS data_type,
			--a.data_type AS data_type,
			LTRIM(RTRIM(a.character_maximum_length))		AS character_maximum_length,
			LTRIM(RTRIM(a.numeric_scale))					AS numeric_scale,
			LTRIM(RTRIM(a.numeric_precision))				AS numeric_precision,
			--b.primary_key_definition,
			CASE WHEN b.PK_column_name IS NULL 
			THEN 0 ELSE 1 END								AS is_primary_key,
			''tab''											AS local_schema_name,
			LTRIM(RTRIM(a.table_schema))					AS remote_schema_name,
			''remote''										AS local_or_remote
			FROM OPENQUERY(' +@remote_server_name+ ', 
			''select  
			c.table_name, 
			c.column_name, 
			c.ordinal_position, 
			c.is_nullable, 
			c.data_type, 
			c.udt_name ,
			c.character_maximum_length, 
			c.numeric_scale, 
			c.numeric_precision, 
			c.table_schema
			from information_schema.columns c 	
			where c.table_catalog = ''''workgroup'''' and c.table_schema = ''''public'''''') a
			LEFT JOIN 
			OPENQUERY(' +@remote_server_name+ ', 
			''select 
			cl.relname as table_name, 
			co.conname as constraint_name, 
			co.contype conatraint_type,
			pg_get_constraintdef(co.oid) AS primary_key_definition ,
			ns.nspname as schema_name,
			pa.attname as PK_column_name
			from pg_class cl join pg_constraint co on cl.oid = co.conrelid 
			join pg_namespace ns on cl.relnamespace = ns.oid
			join pg_attribute pa on pa.attrelid = cl.oid and pa.attnum = co.conkey[1] 
			where co.contype = ''''p''''
			and cl.relkind=''''r''''
			and ns.nspname = ''''public'''''') b 
			ON a.table_name = b.table_name AND a.table_schema = b.[schema_name] AND a.column_name = b.PK_column_name			
			WHERE SUBSTRING(a.table_name, 1, 1) <> ''_'' AND SUBSTRING(a.table_name, 1, 7) <> ''orphans''
			AND NOT EXISTS (SELECT objectname FROM TableauDBCopy.dbo.tabSchemaObjectsExclude o WHERE o.objectname = a.table_name)			
			ORDER BY a.table_name, a.ordinal_position'
		

		IF @Is_Debug_Mode = 1
		BEGIN
			PRINT CHAR(13) + 'SQL statement for acquiring ''source'' tables metadata into #t_allTblMetadata temp table:'
			PRINT '-----------------------------------------------------------------------------------------------'
			PRINT @SQL +REPLICATE(CHAR(13),2) 
		END

		EXEC(@SQL)

		IF @Is_Debug_Mode = 1 
			BEGIN
				SELECT  '#t_allTblMetadata table content for remote objects metadata:' AS 'HINT'
                SELECT  *
                FROM    #t_allTblMetadata WHERE local_or_remote = 'Remote'
				ORDER BY table_name, ordinal_position
			END
		
        IF @Is_ReCheck = 1
            BEGIN
                GOTO Check_Local_Schema
            END

        Check_Local_Schema:  


		SET @SQL = 
		'INSERT INTO #t_allTblMetadata
				(
					[table_name]
					,[column_name]
					,[ordinal_position]
					,[is_nullable]
					,[data_type]
					,[character_maximum_length]
					,[numeric_scale]
					,[numeric_precision]
					,[is_primary_key]
					,[local_schema_name]
					,[remote_schema_name]
					,[local_or_remote]
				)		
        SELECT  
				t.name AS table_name ,
				c.name AS column_name ,
				c.column_id AS ordinal_position ,
				c.is_nullable ,										
				tp.name AS data_type ,
				c.max_length AS character_maximum_length ,
				c.scale AS numeric_scale ,
				c.precision AS numeric_precision ,
				ISNULL(idx.pk_flag,0) as ''is_primary_key'' ,
				ss.name ,
				''public'' ,
				''local'' AS local_or_remote
		FROM    sys.tables t
		JOIN sys.columns c ON t.object_id = c.object_id
		JOIN sys.types tp ON c.user_type_id = tp.user_type_id
		JOIN sys.objects so ON so.object_id = t.object_id
		JOIN sys.schemas ss ON so.schema_id = ss.schema_id
		LEFT JOIN		(select i.name as index_name, i.is_primary_key as pk_flag, OBJECT_NAME(ic.OBJECT_ID) AS table_name,
		COL_NAME(ic.OBJECT_ID,ic.column_id) AS column_name FROM sys.indexes AS i INNER JOIN 
		sys.index_columns AS ic ON  i.OBJECT_ID = ic.OBJECT_ID
		AND i.index_id = ic.index_id
		WHERE   i.is_primary_key = 1) idx on idx.table_name = t.name and idx.column_name = c.name
		JOIN INFORMATION_SCHEMA.TABLES tt on tt.table_schema = ss.name and tt.table_name = t.name
        WHERE   t.type = ''u'' 	
		AND tt.TABLE_CATALOG = 	'''+@Target_DB_Name+'''		 
		AND ss.name = '''+@Target_DB_Schema_Name+''''

		IF @Is_Debug_Mode = 1
		BEGIN
			PRINT 'SQL statement for acquiring ''target'' tables metadata into #t_allTblMetadata temp table:'
			PRINT '-----------------------------------------------------------------------------------------------'
			PRINT @SQL +REPLICATE(CHAR(13),2) 
		END

		EXEC(@SQL)

		IF @Is_Debug_Mode = 1 
			BEGIN
				SELECT  '#t_allTblMetadata table content for local objects metadata:' AS 'HINT'
                SELECT  *
                FROM    #t_allTblMetadata WHERE local_or_remote = 'local'
				ORDER BY table_name, ordinal_position
			END


        IF OBJECT_ID('tempdb..#t_sql') IS NOT NULL
            BEGIN
                DROP TABLE [#t_sql]
            END

        SELECT  DISTINCT
                t1.table_name AS Table_Name ,
                t1.local_schema_name AS Local_Schema_Name ,
                'create table [' + t1.local_schema_name + '].['
                + LOWER(t1.table_name) + '] (' + STUFF(o.list, LEN(o.list), 1, '')
                + ')' + CASE WHEN t2.is_primary_key = 0 THEN ''
                             ELSE '; ALTER TABLE   [' + t1.local_schema_name
                                  + '].[' + t1.table_name + '] '
                                  + ' ADD CONSTRAINT pk_'
                                  + LOWER(t1.local_schema_name) + '_'
                                  + LOWER(t2.table_name) + '_' +  
								  LOWER(REPLACE(t2.pk_column_names,',','_'))
                                  +' PRIMARY KEY CLUSTERED ' + '('
                                  + LOWER(t2.pk_column_names) + ')'
                        END AS Create_Table_Schema_Definition_SQL ,
                'if object_id (''[' + t1.local_schema_name + '].['
                + t1.table_name + ']' + ''', ''U'') IS NOT NULL drop table ['
                + t1.local_schema_name + '].[' + t1.table_name + ']' AS Drop_Table_SQL
        INTO    #t_sql
        FROM    #t_allTblMetadata t1
                CROSS APPLY ( SELECT    '[' + column_name + '] '
                                        +	CASE	WHEN data_type IN ( 'bigint',
																		'int8',
																		'bigserial')
													THEN				'bigint'
													WHEN data_type IN (	'integer',
																		'serial4', 
																		'serial',
																		'int4',
																		'int',
																		'oid')
													THEN				'int'
													WHEN data_type IN ( 'smallint', 
																		'serial2', 
																		'smallserial',
																		'int2')
													THEN				'smallint'
													WHEN data_type IN ( 'uuid')
													THEN				'uniqueidentifier'	
													WHEN data_type IN (	'bool', 
																		'boolean' )
													THEN				'bit'
													WHEN data_type IN (	'timestamp', 
																		'timestamptz')
													THEN				'datetime'
													WHEN data_type IN ( 'bytea',
																		'json',
																		'text',
																		'varchar')
													THEN				'nvarchar'
													WHEN data_type IN ( SELECT * FROM #t_seqfloats )																	
													THEN				'float'
													ELSE data_type 
													END									
                                        +	CASE	WHEN data_type	IN ('int2',
																		'int4',
																		'int8',
																		'oid',																		
																		'timestamp',																	
																		'uuid',
																		'bool')
													THEN ''
													WHEN 
													data_type IN ('text', 'json', 'bytea') OR (data_type = 'varchar' and character_maximum_length IS NULL) OR character_maximum_length > 8000
													THEN '(max)'			 							  
													WHEN data_type = 'decimal'
													THEN '('
                                                    + CAST(numeric_precision AS VARCHAR)
                                                    + ', '
                                                    + CAST(numeric_scale AS VARCHAR)
                                                    + ')'
													WHEN data_type in (SELECT * FROM #t_seqfloats)
													THEN '(53)'
													ELSE COALESCE('(' + CAST(character_maximum_length AS VARCHAR) + ')', '')
                                          END + ' '
                                        +( CASE WHEN is_nullable = 0
                                                THEN 'NOT '
                                                ELSE ''
                                           END ) + 'NULL' + ','
                              FROM      #t_allTblMetadata
                              WHERE     table_name = t1.table_name AND local_or_remote = 'Remote'
                              ORDER BY  ordinal_position
                            FOR
                              XML PATH('')
                            ) o ( list )
                JOIN ( SELECT   table_name ,
                                is_primary_key ,
                                pk_column_names ,
                                column_name = REVERSE(RIGHT(REVERSE(pk_column_names),
                                                            LEN(pk_column_names)
                                                            - CHARINDEX(',',
                                                              REVERSE(pk_column_names))))
                       FROM     ( SELECT    table_name ,
                                            is_primary_key ,
                                            pk_column_names = STUFF(( SELECT
                                                              ','
                                                              +CAST(column_name AS VARCHAR(500))
                                                              FROM
                                                              #t_allTblMetadata z2
                                                              WHERE
                                                              z1.table_name = z2.table_name
                                                              AND z2.is_primary_key = 1
															  AND z2.local_or_remote = 'Remote'
															  ORDER BY z2.column_name ASC
                                                              FOR
                                                              XML
                                                              PATH('')
                                                              ), 1, 1, '')
                                  FROM      #t_allTblMetadata z1
                                  WHERE     z1.is_primary_key = 1
											AND z1.local_or_remote = 'Remote'
                                  GROUP BY  z1.table_name ,
                                            z1.is_primary_key
                                ) a
                     ) t2 ON t1.table_name = t2.table_name
        WHERE   t1.local_schema_name <> 'unknown' and t1.local_or_remote = 'Remote'

        IF @Is_Debug_Mode = 1
            BEGIN
                SELECT  '#t_sql table content:' AS 'HINT'
               SELECT  *
                FROM    #t_sql
				ORDER BY Table_Name 
            END

        IF @Is_ReCheck = 1
            BEGIN
                GOTO Do_Table_Diff
            END



        Do_Table_Diff:


        IF OBJECT_ID('tempdb..#t_diff') IS NOT NULL
            BEGIN
                DROP TABLE [#t_diff]
            END

			  
        ;WITH    Temp_CTE ( table_name, column_name, is_nullable, data_type, local_schema_name, is_primary_key, character_maximum_length, numeric_scale, numeric_precision )
                  AS (			  				  				 				 
                       SELECT	table_name					= m.table_name ,
								column_name					= m.column_name ,
                                is_nullable					= m.is_nullable ,
                                data_type					= CASE	WHEN m.data_type IN (	'bigint',
																							'int8',
																							'bigserial')
																	THEN					'bigint'
																	WHEN m.data_type IN (	'integer',
																							'serial4', 
																							'serial',
																							'int4',
																							'int',
																							'oid')
																	THEN					'int'
																	WHEN m.data_type IN (	'smallint', 
																							'serial2', 
																							'smallserial',
																							'int2')
																	THEN					'smallint'
																	WHEN m.data_type IN (	'uuid')
																	THEN					'uniqueidentifier'	
																	WHEN m.data_type IN (	'bool', 
																							'boolean' )
																	THEN					'bit'
																	WHEN m.data_type IN (	'timestamp', 
																							'timestamptz')
																	THEN					'datetime'
																	WHEN m.data_type IN (	'bytea',
																							'json',
																							'text',
																							'varchar')
																	THEN					'nvarchar'
																	WHEN m.data_type IN ( SELECT * FROM #t_seqfloats )																	
																	THEN					'float'
																	ELSE m.data_type 
															END,
                                local_schema_name			= m.local_schema_name ,
                                is_primary_key				= m.is_primary_key ,
                                character_maximum_length	= COALESCE(CASE WHEN 
																		m.data_type IN ('text', 'json', 'bytea') OR (m.data_type = 'varchar' and m.character_maximum_length IS NULL) OR m.character_maximum_length > 8000
																			THEN 'max' 
																			ELSE CAST(m.character_maximum_length AS VARCHAR) END,
																			constants.character_maximum_length ,
																			CAST(l.character_maximum_length AS VARCHAR)),
                                numeric_scale				= COALESCE(	constants.numeric_scale, 
																		CAST(m.numeric_scale AS VARCHAR),
																		CAST(l.numeric_scale AS VARCHAR)),
								numeric_precision			= COALESCE(	constants.numeric_precision, 
																		CAST(m.numeric_precision AS VARCHAR), 
																		CAST(l.numeric_precision AS VARCHAR))
                       FROM     #t_allTblMetadata m
                                LEFT JOIN ( SELECT  'char' AS data_type ,
                                                    NULL AS character_maximum_length ,
                                                    0 AS numeric_scale ,
                                                    0 AS numeric_precision
                                            UNION ALL
                                            SELECT  'varchar' ,
                                                    NULL ,
                                                    '0' ,
                                                    '0'
											UNION ALL
                                            SELECT  'time' ,
                                                    '5' ,
                                                    '7' ,
                                                    '16'
                                            UNION ALL
                                            SELECT  'date' ,
                                                    '3' ,
                                                    '0' ,
                                                    '10'
                                            UNION ALL
                                            SELECT  'datetime' ,
                                                    '8' ,
                                                    '3' ,
                                                    '23'
                                            UNION ALL
                                            SELECT  'datetime2' ,
                                                    '8' ,
                                                    '7' ,
                                                    '27'
                                            UNION ALL
                                            SELECT  'smalldatetime' ,
                                                    '4' ,
                                                    '0' ,
                                                    '16'
                                            UNION ALL
                                            SELECT  'bit' ,
                                                    '1' ,
                                                    '0' ,
                                                    '1'
                                            UNION ALL
                                            SELECT  'float' ,
                                                    '8' ,
                                                    '0' ,
                                                    '53'
                                            UNION ALL
                                            SELECT  'money' ,
                                                    '8' ,
                                                    '4' ,
                                                    '19'
                                            UNION ALL
                                            SELECT  'smallmoney' ,
                                                    '4' ,
                                                    '4' ,
                                                    '10'
                                            UNION ALL
                                            SELECT  'uniqueidentifier' ,
                                                    '16' ,
                                                    '0' ,
                                                    '0'
                                            UNION ALL
                                            SELECT  'xml' ,
                                                    'max' ,
                                                    '0' ,
                                                    '0'
                                            UNION ALL
                                            SELECT  'numeric' ,
                                                    '9' ,
                                                    '0' ,
                                                    '18'
                                            UNION ALL
                                            SELECT  'real' ,
                                                    '4' ,
                                                    '0' ,
                                                    '24'
                                            UNION ALL
                                            SELECT  'tinyint' ,
                                                    '1' ,
                                                    '0' ,
                                                    '3'
                                            UNION ALL
                                            SELECT  'smallint' ,
                                                    '2' ,
                                                    '0' ,
                                                    '5'
                                            UNION ALL
                                            SELECT  'int' ,
                                                    '4' ,
                                                    '0' ,
                                                    '10'
                                            UNION ALL
                                            SELECT  'bigint' ,
                                                    '8' ,
                                                    '0' ,
                                                    '19'
                                          ) constants ON	(CASE	WHEN m.data_type IN (		'bigint',
																								'int8',
																								'bigserial')
																	THEN						'bigint'
																	WHEN m.data_type IN (		'integer',
																								'serial4', 
																								'serial',
																								'int4',
																								'int',
																								'oid')
																	THEN						'int'
																	WHEN m.data_type IN (		'smallint', 
																								'serial2', 
																								'smallserial',
																								'int2')
																	THEN						'smallint'
																	WHEN m.data_type IN (		'uuid')
																	THEN						'uniqueidentifier'	
																	WHEN m.data_type IN (		'bool', 
																								'boolean' )
																	THEN						'bit'
																	WHEN m.data_type IN (		'timestamp', 
																								'timestamptz')
																	THEN						'datetime'
																	WHEN m.data_type IN (		'bytea',
																								'json',
																								'text',
																								'varchar')
																	THEN						'nvarchar'
																	WHEN m.data_type IN ( SELECT * FROM #t_seqfloats )																	
																	THEN						'float'
																	ELSE m.data_type 
															END	) = constants.data_type
                                LEFT JOIN #t_allTblMetadata l ON l.column_name = m.column_name
                                                        AND l.table_name = m.table_name
                                                        AND l.data_type = ( CASE	WHEN m.data_type IN (	'bigint',
																											'int8',
																											'bigserial')
																					THEN					'bigint'
																					WHEN m.data_type IN (	'integer',
																											'serial4', 
																											'serial',
																											'int4',
																											'int',
																											'oid')
																					THEN					'int'
																					WHEN m.data_type IN (	'smallint', 
																											'serial2', 
																											'smallserial',
																											'int2')
																					THEN					'smallint'
																					WHEN m.data_type IN (	'uuid')
																					THEN					'uniqueidentifier'	
																					WHEN m.data_type IN (	'bool', 
																											'boolean' )
																					THEN					'bit'
																					WHEN m.data_type IN (	'timestamp', 
																											'timestamptz')
																					THEN					'datetime'
																					WHEN m.data_type IN (	'bytea',
																											'json',
																											'text',
																											'varchar')
																					THEN					'nvarchar'
																					WHEN m.data_type IN ( SELECT * FROM #t_seqfloats )																	
																					THEN					'float'
																					ELSE m.data_type 
																			END ) AND l.local_or_remote = 'Local'
			WHERE m.local_or_remote = 'Remote' 		
			EXCEPT
			SELECT				table_name ,
                                column_name ,
                                is_nullable ,
                                data_type , 
                                local_schema_name ,
                                is_primary_key ,
                                CASE	WHEN character_maximum_length > 8000 OR character_maximum_length = -1
								THEN 'max'
								WHEN data_type IN ('nvarchar', 'nchar') THEN CAST(character_maximum_length/2 AS VARCHAR)
								ELSE CAST(character_maximum_length AS VARCHAR) END AS character_maximum_length,
                                numeric_scale ,
                                numeric_precision
			FROM     #t_allTblMetadata 
			WHERE local_or_remote  ='Local' 
                     )
            SELECT DISTINCT
                    table_name ,
                    local_schema_name
            INTO    #t_diff
            FROM    Temp_CTE

        IF @Is_Debug_Mode = 1
            BEGIN
                SELECT  '#t_diff table content:' AS 'HINT'
                SELECT  *
                FROM    #t_diff
            END

        IF @Is_ReCheck = 1
            GOTO Results

        Run_SQL:
        IF NOT EXISTS ( SELECT DISTINCT
                                Table_Name ,
                                Local_Schema_Name
                        FROM    #t_sql a
                        WHERE   EXISTS ( SELECT table_name
                                         FROM   #t_diff i
                                         WHERE  a.Table_Name = i.table_name ) )
            BEGIN
                GOTO Schema_Diff_ReCheck
            END
        ELSE
            BEGIN
                DECLARE @schema_name VARCHAR(50)
                DECLARE @table_name VARCHAR(256)
                DECLARE @sql_select_dropcreate NVARCHAR(MAX)			

                DECLARE db_cursor CURSOR FORWARD_ONLY
                FOR
                    SELECT DISTINCT
                            Table_Name ,
                            Local_Schema_Name
                    FROM    #t_sql a
                    WHERE   EXISTS ( SELECT table_name
                                     FROM   #t_diff i
                                     WHERE  a.Table_Name = i.table_name )
                OPEN db_cursor
                FETCH NEXT
			FROM db_cursor INTO @table_name, @schema_name
                WHILE @@FETCH_STATUS = 0
                    BEGIN
                        BEGIN TRY
                            BEGIN TRANSACTION
                            SET @sql_select_dropcreate = ( SELECT
                                                              Drop_Table_SQL
                                                           FROM
                                                              #t_sql 
                                                           WHERE
                                                              Table_Name = @table_name
                                                         ) + '; ' +CHAR(13)
                                + ( SELECT  Create_Table_Schema_Definition_SQL 
                                    FROM    #t_sql
                                    WHERE   Table_Name = @table_name
                                  ) + REPLICATE(CHAR(13),2)    
								  
							IF @Is_Debug_Mode = 1
								BEGIN
									PRINT 'SQL statement for dropping/recreating ''source'' table(s):'
									PRINT '-----------------------------------------------------------------------------------------------'
									PRINT @sql_select_dropcreate									
								END

                            EXEC sp_sqlexec @sql_select_dropcreate
                            --SET @Is_All_OK = 1
                            SET @Error_Message = 'All Good!'
                            COMMIT TRANSACTION
                        END TRY
                        BEGIN CATCH		
                            IF @@TRANCOUNT > 0
                                ROLLBACK TRANSACTION;
                            SET @Is_All_OK = 0
                            SET @Error_Message = 'This operation has been unexpectandly terminated due to error: '''
                                + ERROR_MESSAGE() + ''' at line '
                                + CAST(ERROR_LINE() AS VARCHAR);								
                        END CATCH
                        FETCH NEXT FROM db_cursor INTO @table_name,@schema_name
                    END
                CLOSE db_cursor
                DEALLOCATE db_cursor
                SET @Is_ReCheck = 1
            END


        Schema_Diff_ReCheck:
        IF @Is_ReCheck = 1
            BEGIN
                GOTO Check_RemoteSvr_Schema
            END

        Results:
        IF EXISTS ( SELECT TOP 1
                            *
                    FROM    #t_diff )
            BEGIN 
                SET @Is_All_OK = 0
                SET @Error_Message = 'Table schema reconciliation between '
                    + '' + @@SERVERNAME + ''
                    + ' and remote database on '''+@remote_server_name+'''' + CHAR(10)
                SET @Error_Message = @Error_Message + 'failed. Please troubleshoot.'
            END
        ELSE
            BEGIN
                SET @Is_All_OK = 1
                SET @Error_Message = 'All Good!'
            END


		IF OBJECT_ID('tempdb..#t_seqfloats') IS NOT NULL
            BEGIN
                DROP TABLE #t_seqfloats		
            END
        IF OBJECT_ID('tempdb..#t_allTblMetadata') IS NOT NULL
            BEGIN
                DROP TABLE [#t_allTblMetadata]
            END 
        IF OBJECT_ID('tempdb..#t_sql') IS NOT NULL
            BEGIN
                DROP TABLE [#t_sql]
            END
        IF OBJECT_ID('tempdb..#t_sql') IS NOT NULL
            BEGIN
                DROP TABLE [#t_diff]
            END	
    END

Finally, we are ready to load the Tableau PostgreSQL data into the ‘TableauDBCopy’ database tables on the ‘tab’ schema. For that we can use SQL Server Integration Services but since the ‘workgroup’ database is quite small in size and most tables have a primary key defined on them, we can load the data in a sequential order i.e. table by table using a modified version of my database replication stored procedure which I described in one of my previous blog posts HERE. The stored procedure works in a similar fashion to the one described previously but allowances needed to be made in order to enable PostgreSQL and SQL Server data types and certain conventions conformance e.g. certain PostgreSQL reserved words need to be encapsulated in double quotes in the OPENQUERY statements in order to be validated and recognized by SQL Server. Likewise, certain SQL Server reserved words need to be used with square brackets delimiters. To reference those exceptions, I have created two views (downloadable from HERE) which are used in the merging stored procedure to provide greater cross-database compatibility. The code to the stored procedure works on a table-to-table basis but it it’s would not very hard to make it loop through a collection of objects e.g. using a cursor or ‘Foreach Loop’ SSIS transformation to automate a comprehensive data load. If, on the other hand, a much faster, asynchronous load is required you can always check out one of my previous blog posts on parallel SQL statements execution using SQL Server Agent jobs HERE. All the code for the data synchronization across Tableau’s PostgreSQL database and SQL Server instance as well as other T-SQL snippets presented in the post can be downloaded from my OneDrive folder HERE.

Below is a short video depicting how this solution works using both – schema synchronisation and data synchronisation stored procedures.

The ‘workgroup’ database data dictionary with all PostgreSQL objects description can be found HERE.

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This entry was posted on Monday, December 7th, 2015 at 9:58 am and is filed under Data Modelling, SQL, SQL Server, Tableau. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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