Performance difference using LIKE between :PARAM and INLINE
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Key: CORE-5740
URL: http://tracker.firebirdsql.org/browse/CORE-5740
Project: Firebird Core
Issue Type: Bug
Affects Versions: 3.0.3
Environment: Local database with Windows 10 and
Firebird-3.0.3.32900-0_x64
Reporter: Rafael Dipold
I have a local database with 1.2 million "PARCEIROS" records. The NOME is a
index column declared as:
NOME VARCHAR(50) CHARACTER SET ISO8859_1 NOT NULL COLLATE PT_BR
Using ibexpert, there are substancial performance difference using LIKE between
1 and 2 SQL modes above with same PLAN:
**STARTING doesn´t occur the same problem.
-----------------------------------------
--1. When I Inform 'RAFAEL%' in SQL inline
-----------------------------------------
SELECT NOME
FROM PARCEIROS
WHERE (NOME LIKE 'RAFAEL%')
ORDER BY NOME
-----------------------------------------
Plan
PLAN (PARCEIROS ORDER K_PARCEIROS_NOME_ASC)
------ Performance info ------
Prepare time = 16ms
Execute time = 16ms
Avg fetch time = 0,70 ms
Current memory = 21.836.360
Max memory = 25.249.672
Memory buffers = 2.048
Reads from disk to cache = 1.911
Writes from cache to disk = 0
Fetches from cache = 6.043
-----------------------------------------
--2. When I Inform 'RAFAEL%' in the NOME param
-----------------------------------------
SELECT NOME
FROM PARCEIROS
WHERE (NOME LIKE :NOME)
ORDER BY NOME
-----------------------------------------
Plan
PLAN (PARCEIROS ORDER K_PARCEIROS_NOME_ASC)
------ Performance info ------
Prepare time = 31ms
Execute time = 15s 156ms
Avg fetch time = 658,96 ms
Current memory = 24.125.112
Max memory = 25.249.672
Memory buffers = 2.048
Reads from disk to cache = 926.161
Writes from cache to disk = 1
Fetches from cache = 2.992.118
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