Question

I have a query that selects any information from a db. This information I will use for defining the article price. The problem is that the query takes 3 seconds to execute. This time must to be multiply for many article.

How can I optimize this query? In the articoli table there are 16 330 rows.

This is the query

SELECT ts_scon, AI_CODICIVA, 
       AI_LIS_EURO1, AI_LIS_EURO2, 
       AI_LIS_EURO3, AI_LIS_EURO4, 
       AI_LIS_EURO5, cl_tipocl
  FROM tabscon, articoli, clienti
 WHERE ts_azienda = 'SRL' 
   AND AI_AZIENDA = 'SRL'
   AND AI_CODIREST = $cod_articolo 
   AND cl_azienda = 'SRL' 
   AND cl_codice = $cod_cliente
   AND ts_codice IN (
        SELECT cl_tabsco 
          FROM clienti 
         WHERE cl_codice = $cod_cliente 
           AND CL_AZIENDA = 'SRL')
   AND ts_grusco IN (
        SELECT ai_grupscon 
          FROM articoli 
         WHERE ai_codirest = $cod_articolo  
           AND AI_AZIENDA = 'SRL')

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This is the EXPLAIN result. The results are the same with indices that without indices.

id|select_type|table|type|possible_keys|key|key_len|ref|rows|Extra
1|PRIMARY|clienti|const|PRIMARY|PRIMARY|25|const,const|1
1|PRIMARY|tabscon|ref|PRIMARY,azie_grsco_codice|PRIMARY|15|const|505|Using where
1|PRIMARY|articoli|ALL|PRIMARY,barcodeidx,StatoAidx,Statoidx|NULL|NULL|NULL|16333|Using where; Using join buffer
3|DEPENDENT SUBQUERY|articoli|ref|PRIMARY,barcodeidx,StatoAidx,Statoidx StatoAidx|15|const|7311|Using where
2|DEPENDENT|SUBQUERY|clienti|const|PRIMARY

Sorry for the little order but not yet practical.

Answer 1

Query-wise the best way to do this would be.

SELECT ts_scon, a.AI_CODICIVA, 
  a.AI_LIS_EURO1, a.AI_LIS_EURO2, 
  a.AI_LIS_EURO3, a.AI_LIS_EURO4, 
  a.AI_LIS_EURO5, c.cl_tipocl
FROM tabscon t
JOIN articoli a ON ts_azienda = ai_azienda
JOIN articoli a2 ON ts_azienda = a2.ai_azienda AND a2.ai_codirest = $cod_articolo AND a2.ai_grusco = ts_grusco
JOIN clienti c ON ai_azienda = cl_azienda
JOIN clienti c2 ON ai_azienda = c2.cl_azienda AND c2.cl_codice = $cod_cliente AND c2.cl_tabsco = ts_codice
WHERE ts_azienda = 'SRL' 
AND AI_CODIREST = $cod_articolo

That said, I’m not sure exactly what information you’re trying to get here; you may not need to join onto those tables twice, but without understanding the data I can’t be sure.