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bobbo asked

Select statement is too slow

Hi, My SELECT takes too long to execute. It takes about 8 sec and this is not ok. Does anybody know if and how I should rewrite the SELECT to get it faster? SELECT ID_ACNT_CT_CRD, PA_PRS.NM_PRS_OFCL AS NAME, CARD_INFO.EXT_SC_ACNT_CT_CRD, ADDR.EXT_A2_ADS, ADDR.EXT_PC_CNCT, ADDR.EXT_CI_CNCT, ID_ACNT_CT_CRD, min(CN.CN_INF_VALUE) AS CONTACT FROM PA_PRS JOIN PA_PRTY ON PA_PRS.ID_PRTY_PRS = PA_PRTY.ID_PRTY JOIN PA_RO_PRTY ON PA_PRTY.ID_PRTY = PA_RO_PRTY.ID_PRTY LEFT JOIN LO_PRTY_CN_INF CN ON PA_RO_PRTY.ID_PRTY = CN.ID_PRTY JOIN LO_PRTY_ADS ADDR ON PA_RO_PRTY.ID_PRTY = ADDR.ID_PRTY JOIN PA_CT ON PA_RO_PRTY.ID_PRTY = PA_CT.ID_PRTY JOIN LE_CTAC ON PA_CT.ID_CT = LE_CTAC.ID_CT JOIN EXT_ACNT_CT_CRD_CTAC_AFLN CARD_AFLN ON LE_CTAC.ID_CTAC = CARD_AFLN.ID_CTAC JOIN LE_ACNT_CT_CRD CARD_INFO ON CARD_AFLN.ID_ACNT_CT_CRD = CARD_INFO.AI_ACNT_CT_CRD WHERE LOWER(CARD_AFLN.ID_ACNT_CT_CRD) like '%%' AND PA_PRS.NM_PRS_OFCL like '%bygg%' AND LOWER(ADDR.EXT_A2_ADS)like '%%' AND LOWER(ADDR.EXT_PC_CNCT)like '%%' AND LOWER(ADDR.EXT_CI_CNCT)like '%%' AND (LOWER(CN.CN_INF_VALUE) like '%%' OR '%%'='%%') GROUP BY ID_ACNT_CT_CRD, PA_PRS.NM_PRS_OFCL,EXT_SC_ACNT_CT_CRD, EXT_A2_ADS limit 500
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5 comments
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should there be text within the LIKE clauses. At the moment you have LIKE '%%' - which will just match everything.
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Sorry for reply to your question with a question, but what is this bit doing? (LOWER(CN.CN_INF_VALUE) like '%%' OR '%%'='%%')
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Well, the reason is to match everything in the DB whit the word %%bygg%% And the answer to the question about the string (LOWER(CN.CN_INF_VALUE) like '%%' OR '%%'='%%') I really dont know!! Its a earlier developer from India who have write that bit :(
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Another thing you can do is index the tables based on their joining fields. (Note indexing will result in the table taking up more space and when you INSERT or UPDATE data you may notice a delay as the indexes have to reorder)
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mjharper answered
I would think the query below would give the same results. Hard to say what impact it will have on the performance. You'd probably need to provide the queryplan along with the query for people to help you with that. SELECT ID_ACNT_CT_CRD, PA_PRS.NM_PRS_OFCL AS NAME, CARD_INFO.EXT_SC_ACNT_CT_CRD, ADDR.EXT_A2_ADS, ADDR.EXT_PC_CNCT, ADDR.EXT_CI_CNCT, ID_ACNT_CT_CRD, min(CN.CN_INF_VALUE) AS CONTACT FROM PA_PRS JOIN PA_PRTY ON PA_PRS.ID_PRTY_PRS = PA_PRTY.ID_PRTY JOIN PA_RO_PRTY ON PA_PRTY.ID_PRTY = PA_RO_PRTY.ID_PRTY LEFT JOIN LO_PRTY_CN_INF CN ON PA_RO_PRTY.ID_PRTY = CN.ID_PRTY JOIN LO_PRTY_ADS ADDR ON PA_RO_PRTY.ID_PRTY = ADDR.ID_PRTY JOIN PA_CT ON PA_RO_PRTY.ID_PRTY = PA_CT.ID_PRTY JOIN LE_CTAC ON PA_CT.ID_CT = LE_CTAC.ID_CT JOIN EXT_ACNT_CT_CRD_CTAC_AFLN CARD_AFLN ON LE_CTAC.ID_CTAC = CARD_AFLN.ID_CTAC JOIN LE_ACNT_CT_CRD CARD_INFO ON CARD_AFLN.ID_ACNT_CT_CRD = CARD_INFO.AI_ACNT_CT_CRD WHERE PA_PRS.NM_PRS_OFCL LIKE '%bygg%' GROUP BY ID_ACNT_CT_CRD, PA_PRS.NM_PRS_OFCL, EXT_SC_ACNT_CT_CRD, EXT_A2_ADS LIMIT 500 ammended query to check for NOT NULL as suggested in comments... SELECT ID_ACNT_CT_CRD, PA_PRS.NM_PRS_OFCL AS NAME, CARD_INFO.EXT_SC_ACNT_CT_CRD, ADDR.EXT_A2_ADS, ADDR.EXT_PC_CNCT, ADDR.EXT_CI_CNCT, ID_ACNT_CT_CRD, min(CN.CN_INF_VALUE) AS CONTACT FROM PA_PRS JOIN PA_PRTY ON PA_PRS.ID_PRTY_PRS = PA_PRTY.ID_PRTY JOIN PA_RO_PRTY ON PA_PRTY.ID_PRTY = PA_RO_PRTY.ID_PRTY LEFT JOIN LO_PRTY_CN_INF CN ON PA_RO_PRTY.ID_PRTY = CN.ID_PRTY JOIN LO_PRTY_ADS ADDR ON PA_RO_PRTY.ID_PRTY = ADDR.ID_PRTY JOIN PA_CT ON PA_RO_PRTY.ID_PRTY = PA_CT.ID_PRTY JOIN LE_CTAC ON PA_CT.ID_CT = LE_CTAC.ID_CT JOIN EXT_ACNT_CT_CRD_CTAC_AFLN CARD_AFLN ON LE_CTAC.ID_CTAC = CARD_AFLN.ID_CTAC JOIN LE_ACNT_CT_CRD CARD_INFO ON CARD_AFLN.ID_ACNT_CT_CRD = CARD_INFO.AI_ACNT_CT_CRD WHERE CARD_AFLN.ID_ACNT_CT_CRD IS NOT NULL AND PA_PRS.NM_PRS_OFCL LIKE '%bygg%' AND ADDR.EXT_A2_ADS IS NOT NULL AND ADDR.EXT_PC_CNCT IS NOT NULL AND ADDR.EXT_CI_CNCT IS NOT NULL GROUP BY ID_ACNT_CT_CRD, PA_PRS.NM_PRS_OFCL, EXT_SC_ACNT_CT_CRD, EXT_A2_ADS LIMIT 500
6 comments
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This will not ignore NULL values I *think* that: LOWER(ADDR.EXT_PC_CNCT)like '%%' is really: ADDR.EXT_PC_CNCT IS NOT NULL So where you have just ignored this you could get more data back then bobbo wants
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Good spot Gazz. I've added an ammended query to include the check for NOT NULL.
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Thanks, but it is still going way to slow now 7,3 sec. U have any more ideas?
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Whats a queryplan?
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The queryplan tells you how SQL will execute your query. For example what indexes will get used etc. There's an introduction to them here: https://www.simple-talk.com/sql/performance/execution-plan-basics/ You can see it by pressing CTRL+L in SSMS and can save it from there.
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the question is tagged mysql. running the query prefixed with the EXPLAIN keyword (or EXPLAIN EXTENDED) will give you the mysql equivalent of a SQL Server query plan. Here is an EXPLAIN introductory article - http://www.sitepoint.com/using-explain-to-write-better-mysql-queries/
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bobbo answered
Is it also comment to use join multiple times as in this question? Is it maybe why it is slow?
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