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sp_sync_get_new_rows.sql
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sp_sync_get_new_rows.sql
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/**********************************************************************************************
Purpose: Get new rows from source table and insert them into a target table
Notes: * Useful for keeping a up-to-date Redshift copy of a remote Federated table
* Insert any rows from a source table with an ID higher than the max in the target table
* Source and target tables must have same table structure (column order and data types)
Parameters:
batch_time: Timestamp for this batch. Used to timestamp the log
source_tbl: Schema qualified name of external source table
target_tbl: Schema qualified name of local target table
id_column : Name of auto-incrementing ID column used to find new rows
log_table : Schema qualified name of table where actions are logged
CREATE TABLE $(log_table) (
batch_time TIMESTAMP
, source_table VARCHAR
, target_table VARCHAR
, sync_column VARCHAR
, sync_status VARCHAR
, sync_queries VARCHAR --Query ID of the INSERT
, row_count INT);
max_rows : Maximum number of rows allowed to sync automatically
History:
2020-04-01 - joeharris76 - Created
**********************************************************************************************/
-- DROP PROCEDURE sp_sync_get_new_rows(TIMESTAMP,VARCHAR,VARCHAR,VARCHAR,VARCHAR,BIGINT);
CREATE OR REPLACE PROCEDURE sp_sync_get_new_rows (
batch_time IN TIMESTAMP
, source_tbl IN VARCHAR(256) --Schema qualified with external schema
, target_tbl IN VARCHAR(256) --Schema qualified or `public` is assumed
, id_column IN VARCHAR(128)
, log_table IN VARCHAR(256)
, max_rows IN BIGINT)
AS $$
DECLARE
sql VARCHAR(MAX) := '';
rs_tbl VARCHAR := '';
rs_schm VARCHAR := '';
is_numeric BOOLEAN := FALSE;
max_id BIGINT := 0;
insert_query VARCHAR := '';
insert_count INTEGER := 0;
BEGIN
-- Check that required parameters are set
IF source_tbl='' OR target_tbl='' OR id_column='' OR log_table='' OR max_rows='' THEN
EXECUTE 'INSERT INTO '||log_table||' (batch_time, source_table, target_table, sync_column, sync_status, sync_queries, row_count)'||
' SELECT '''||batch_time||''','''||source_tbl||''','''||target_tbl||''','''||id_column||
''',''ABORT - Empty parameters'','''||insert_query||''','||insert_count||';';
COMMIT; --Persist the log entry
RAISE EXCEPTION 'Aborted - required parameters are missing.';
END IF;
-- Notify user when max_rows is specified
IF max_rows <> 0 THEN
RAISE INFO 'A maximum of % rows will be inserted.', max_rows;
END IF;
-- Split `target_tbl` into `rs_schm` and `rs_tbl` as needed
IF CHARINDEX('.',target_tbl) > 0 THEN
SELECT INTO rs_schm SPLIT_PART(target_tbl,'.',1);
SELECT INTO rs_tbl SPLIT_PART(target_tbl,'.',2);
ELSE
rs_schm := 'public';
rs_tbl := target_tbl;
END IF;
--Check that `id_column` is a numeric value
sql := 'SELECT CASE WHEN a.atttypid IN (20,21,23,700,701,1700) THEN TRUE ELSE FALSE END '||
' FROM pg_attribute a '||
' JOIN pg_class b ON a.attrelid = b.relfilenode '||
' JOIN pg_namespace c ON b.relnamespace = c.oid '||
' WHERE TRIM(a.attname) = '''||quote_ident(id_column)||''''||
' AND TRIM(c.nspname) = '''||rs_schm||''''||
' AND TRIM(b.relname) = '''||rs_tbl||''''||
'LIMIT 1;';
EXECUTE sql INTO is_numeric;
IF is_numeric IS FALSE THEN
EXECUTE 'INSERT INTO '||log_table||' (batch_time, source_table, target_table, sync_column, sync_status, sync_queries, row_count)'||
' SELECT '''||batch_time||''','''||source_tbl||''','''||target_tbl||''','''||id_column||
''',''ABORT - `id_column` is not numeric'','''||insert_query||''','||insert_count||';';
COMMIT; --Persist the log entry
RAISE EXCEPTION 'Aborted - `%` is not a numeric column.', id_column;
END IF;
--Get the max value of `id_column` in `target_tbl`
sql := 'SELECT MAX('||id_column||') FROM '||target_tbl||' ;';
EXECUTE sql INTO max_id;
IF max_id = 0 OR max_id IS NULL THEN
EXECUTE 'INSERT INTO '||log_table||' (batch_time, source_table, target_table, sync_column, sync_status, sync_queries, row_count)'||
' SELECT '''||batch_time||''','''||source_tbl||''','''||target_tbl||''','''||id_column||
''',''ABORT - Invalid `max_id`'','''||insert_query||''','||insert_count||';';
COMMIT; --Persist the log entry
RAISE EXCEPTION 'Aborted - `max_id` was not retrieved correctly.';
END IF;
--Run the insert.
-- Note that we are already inside a transaction
-- We can check `max_rows` against the INSERT row count and roll back if needed
-- This means we SELECT from the source table **just once**.
EXECUTE 'INSERT INTO '||target_tbl||' SELECT * FROM '||source_tbl||' WHERE '||quote_ident(id_column)||' > '||max_id||';';
--Get row count for the INSERT
GET DIAGNOSTICS insert_count := ROW_COUNT;
--Get query id for the INSERT
SELECT INTO insert_query pg_last_query_id();
--Roll back if `max_rows` is set and insert rows exceeds it
IF max_rows <> 0 AND insert_count > max_rows THEN
ROLLBACK;
EXECUTE 'INSERT INTO '||log_table||' (batch_time, source_table, target_table, sync_column, sync_status, sync_queries, row_count)'||
' SELECT '''||batch_time||''','''||source_tbl||''','''||target_tbl||''','''||id_column||
''',''ABORT - Sync exceeds `max_rows`'','''||insert_query||''','||insert_count||';';
COMMIT; --Persist the log entry
RAISE EXCEPTION 'Aborted - Sync row count exceeds `max_rows` value.';
--Otherwise commit the insert and record success
ELSE
IF insert_count > 0 THEN
COMMIT; --Persist the insert
EXECUTE 'INSERT INTO '||log_table||' (batch_time, source_table, target_table, sync_column, sync_status, sync_queries, row_count)'||
' SELECT '''||batch_time||''','''||source_tbl||''','''||target_tbl||''','''||id_column||
''',''SUCCESS'','''||insert_query||''','||insert_count||';';
RAISE INFO 'SUCCESS - % rows inserted.', insert_count;
ELSE
EXECUTE 'INSERT INTO '||log_table||' (batch_time, source_table, target_table, sync_column, sync_status, sync_queries, row_count)'||
' SELECT '''||batch_time||''','''||source_tbl||''','''||target_tbl||''','''||id_column||
''',''SKIPPED'','''||insert_query||''','||insert_count||';';
RAISE INFO 'SKIPPED - No new rows found.';
END IF;
END IF;
END
$$ LANGUAGE plpgsql;
/* Usage Example:
-- Postgres: create source table and populate with data
DROP TABLE IF EXISTS public.pg_tbl;
CREATE TABLE public.pg_tbl (
pk_col INTEGER GENERATED ALWAYS AS IDENTITY PRIMARY KEY
, data_col VARCHAR(20));
INSERT INTO public.pg_tbl (data_col)
VALUES ('aardvark'),('aardvarks'),('aardwolf'),('aardwolves');
-- Redshift: create external schema for federated database
CREATE EXTERNAL SCHEMA IF NOT EXISTS pg_fed
FROM POSTGRES DATABASE 'dev' SCHEMA 'public'
URI 'aurora-postgres-ro.ch1pch0psh0p.us-west-2.rds.amazonaws.com' PORT 8192
IAM_ROLE 'arn:aws:iam::123456789012:role/apg-federation-role'
SECRET_ARN 'arn:aws:secretsmanager:us-west-2:123456789012:secret:apg-federation-secret-187Asd';
-- Redshift: create logging table
DROP TABLE IF EXISTS public.sp_logs;
CREATE TABLE public.sp_logs (
batch_time TIMESTAMP
, source_table VARCHAR
, target_table VARCHAR
, sync_column VARCHAR
, sync_status VARCHAR
, sync_queries VARCHAR
, row_count INT);
-- Redshift: create valid target table and partially populate
DROP TABLE IF EXISTS public.rs_tbl;
CREATE TABLE public.rs_tbl (
pk_col INTEGER
, data_col VARCHAR(20));
INSERT INTO public.rs_tbl
VALUES (1,'aardvark'), (2,'aardvarks');
-- Redshift: create **invalid** target table to test the SP
DROP TABLE IF EXISTS public.rs_invalid;
CREATE TABLE public.rs_invalid (
pk_col VARCHAR(20)
, data_col VARCHAR(20));
-- Redshift: call the stored procedure using the invalid table
CALL sp_sync_get_new_rows(SYSDATE,'pg_fed.pg_tbl','public.rs_invalid','pk_col','public.sp_logs',0);
-- ERROR: Aborted - `pk_col` is not a numeric column.
SELECT * FROM sp_logs ORDER BY batch_time DESC LIMIT 1;
-- -[ RECORD 1 ]+-----------------------------------
-- batch_time | 2020-04-09 20:23:42.856964
-- source_table | apg_100g.pg_tbl
-- target_table | public.rs_invalid
-- sync_column | pk_col
-- sync_status | ABORT - `pk_col` is not numeric
-- sync_queries |
-- row_count | 0
-- Redshift: call the stored procedure with missing parameters
CALL sp_sync_get_new_rows(SYSDATE,'pg_fed.pg_tbl','public.rs_tbl','','public.sp_logs',0);
-- ERROR: Aborted - required parameters are missing.
SELECT * FROM sp_logs ORDER BY batch_time DESC LIMIT 1;
-- -[ RECORD 1 ]+-----------------------------------
-- batch_time | 2020-04-09 20:29:03.486522
-- source_table | apg_100g.pg_tbl
-- target_table | public.rs_tbl
-- sync_column |
-- sync_status | ABORT - Empty parameters
-- sync_queries |
-- row_count | 0
-- Redshift: call the stored procedure with max_rows = 1
CALL sp_sync_get_new_rows(SYSDATE,'pg_fed.pg_tbl','public.rs_tbl','pk_col','public.sp_logs',1);
-- INFO: A maximum of 1 rows will be inserted.
-- ERROR: Aborted - Sync row count exceeds `max_rows` value.
SELECT * FROM sp_logs ORDER BY batch_time DESC LIMIT 1;
-- -[ RECORD 1 ]+-----------------------------------
-- batch_time | 2020-04-09 20:29:44.054005
-- source_table | apg_100g.pg_tbl
-- target_table | public.rs_tbl
-- id_column | pk_col
-- sync_status | ABORT - Sync exceeds `max_rows`
-- sync_queries | 1224588
-- row_count | 2
-- Redshift: call the stored procedure with max_rows unlimited
CALL sp_sync_get_new_rows(SYSDATE,'pg_fed.pg_tbl','public.rs_tbl','pk_col','public.sp_logs',0);
-- INFO: SUCCESS - 2 new rows inserted into `target_tbl`.
SELECT * FROM sp_logs ORDER BY batch_time DESC LIMIT 1;
-- -[ RECORD 1 ]+---------------------------
-- batch_time | 2020-04-09 20:33:17.954014
-- source_table | apg_100g.pg_tbl
-- target_table | public.rs_tbl
-- sync_column | pk_col
-- sync_status | SUCCESS
-- sync_queries | 1224618
-- row_count | 2
-- Redshift: call the stored procedure again - no rows will sync
CALL sp_sync_get_new_rows(SYSDATE,'pg_fed.pg_tbl','public.rs_tbl','pk_col','public.sp_logs',0);
-- INFO: NONE - No new rows found in `source_tbl`
SELECT * FROM sp_logs ORDER BY batch_time DESC LIMIT 1;
-- -[ RECORD 1 ]+-------------------------------
-- batch_time | 2020-04-01 00:01:34.849821
-- source_table | pg_fed.pg_tbl
-- target_table | public.rs_tbl
-- sync_column | pk_col
-- sync_status | SUCCESS
-- sync_queries | <NULL>
-- row_count | 0
*/