Un esquema de DWS que migra la sintaxis CONNECT BY de Oracle

Resumen: Este artículo proporciona una solución de sintaxis CONNECT BY para la migración de GaussDB DWS.

Este artículo se comparte desde Huawei Cloud Community " Migración de GaussDB (DWS) - Compatibilidad de Oracle - Migración CONNECT BY ", autor: un archivo en la parte posterior.

CONECTAR EN NOCYCLE

1) Definición de objeto preestablecido

DROP SCHEMA IF EXISTS "sdifin" CASCADE;
CREATE SCHEMA "sdifin";
DROP TABLE IF EXISTS "sdifin"."ogg_ets_bas_instrument_t_2670";
SET search_path = sdifin;
CREATE TABLE ogg_ets_bas_instrument_t_2670 (
 bas_instrument_id numeric NOT NULL,
 instrument_name character varying(600),
 instrument_parent_id numeric,
 status numeric
)
WITH (enable_hstore=on, orientation=column, compression=yes, enable_delta=false, colversion=2.0, max_batchrow=60000)
DISTRIBUTE BY HASH(bas_instrument_id);
DROP TABLE IF EXISTS "sdifin"."ogg_sectype_2360";
SET search_path = sdifin;
CREATE TABLE ogg_sectype_2360 (
 thekey character varying(18) NOT NULL,
        name character varying(150)
)
WITH (enable_hstore=on, orientation=column, compression=yes, enable_delta=false, colversion=2.0, max_batchrow=60000)
DISTRIBUTE BY REPLICATION;

2) declaración original del oráculo

SELECT
 to_char(i.BAS_INSTRUMENT_ID) AS INSTRUMENT_ID,
 to_char(i.INSTRUMENT_PARENT_ID) AS parent_thekey,
    TRIM(i.INSTRUMENT_NAME) AS INSTRUMENT_NAME,
    SYS_CONNECT_BY_PATH(i.INSTRUMENT_NAME, ';') AS INSTRUMENT_PATH,
    SYS_CONNECT_BY_PATH(i.BAS_INSTRUMENT_ID, '->') AS BAS_ID_PATH,  
 LEVEL AS INSTRUMENT_LEVEL,
    CONNECT_BY_ISCYCLE AS CYCLE_ERROR,
 2670 AS ss_id
 FROM OGG_ETS_BAS_INSTRUMENT_T_2670 i, OGG_SECTYPE_2360 s2
WHERE upper(i.instrument_name) = upper(TRIM(s2.name(+)))
AND s2.thekey IS NULL AND I.STATUS = 1
CONNECT BY NOCYCLE PRIOR i.BAS_INSTRUMENT_ID = i.INSTRUMENT_PARENT_ID
START WITH i.instrument_parent_id IS NULL

plan de ejecucion en oracle

punto clave:

1) Características de la declaración: la cláusula WHERE en la declaración SQL contiene condiciones no asociadas

2) Funciones de ejecución: la prioridad de cálculo de la condición no asociada en la cláusula WHERE es menor que la de CONNECT BY, es decir, estas condiciones se filtrarán después de ejecutar CONNECT BY, como la condición FILTER anterior con id=2

3) Lógica de reescritura equivalente a DWS

WITH RECURSIVE TMP_ETC AS (
 SELECT
 to_char(i.bas_instrument_id) AS instrument_id,
 to_char(i.instrument_parent_id) AS parent_thekey,
        trim(i.instrument_name) AS instrument_name,
 ';'||i.instrument_name AS instrument_path,
 '->'||i.bas_instrument_id AS bas_id_path,
 1 AS instrument_level,
 0 AS cycle_error,
 2670 AS ss_id,
        s2.thekey,
 i.status,
 i.bas_instrument_id AS start_val
 FROM sdifin.ogg_ets_bas_instrument_t_2670 i
 LEFT JOIN sdifin.ogg_sectype_2360 s2 ON upper(trim(i.instrument_name)) = upper(trim(s2.name))
 WHERE i.instrument_parent_id IS NULL
 UNION ALL
 SELECT
 to_char(i.bas_instrument_id) AS instrument_id,
 to_char(i.instrument_parent_id) AS parent_thekey,
        trim(i.instrument_name) AS instrument_name,
        (b.instrument_path ||';'||i.instrument_name) AS instrument_path,
        (b.bas_id_path ||'->'||i.bas_instrument_id) AS bas_id_path,
 b.instrument_level+1 AS instrument_level,
        decode(trim(i.bas_instrument_id)=b.start_val,false,0,1) AS cycle_error,
 2670 AS ss_id,
        s2.thekey,
 i.status,
 b.start_val AS start_val
 FROM sdifin.ogg_ets_bas_instrument_t_2670 i
 LEFT JOIN sdifin.ogg_sectype_2360 s2 ON upper(i.instrument_name) = upper(trim(s2.name))
 INNER JOIN tmp_etc b ON b.instrument_id = i.instrument_parent_id
 WHERE b.cycle_error <> 1
)
SELECT 
 instrument_id,
 parent_thekey,
 instrument_name,
 instrument_path,
 bas_id_path,
 instrument_level,
 cycle_error,
 ss_id
FROM tmp_etc
WHERE thekey IS NULL
AND status = 1

 

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