liuchaoheliang opened a new issue #8686:
URL: https://github.com/apache/shardingsphere/issues/8686
version 5.x
when I was testing and parsing a large sql, use the same engine , new
SQLStatementParserEngine("MySQL"), do 50 times parse. watch the cost time,
i found The first few times are much more time-consuming than the subsequent
analysis. why ?
my java code like this:
@Test
public void test() {
String sql = "select ........";
SQLStatementParserEngine engine = new
SQLStatementParserEngine("MySQL");
int i = 0;
while (i < 50){
Long now = System.currentTimeMillis();
engine.parse(sql, false);
Long cost = System.currentTimeMillis() - now;
System.out.println("cost:" + cost);
i++;
}
}
RESULT:
times: 0,cost(ms):1097
times: 1,cost(ms):11
times: 2,cost(ms):13
times: 3,cost(ms):8
times: 4,cost(ms):9
times: 5,cost(ms):4
times: 6,cost(ms):3
times: 7,cost(ms):3
times: 8,cost(ms):3
times: 9,cost(ms):4
times: 10,cost(ms):9
times: 11,cost(ms):4
times: 12,cost(ms):3
times: 13,cost(ms):2
times: 14,cost(ms):2
times: 15,cost(ms):5
times: 16,cost(ms):3
times: 17,cost(ms):3
times: 18,cost(ms):2
times: 19,cost(ms):1
times: 20,cost(ms):3
.......
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