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Posted to issues@calcite.apache.org by "Julian Hyde (JIRA)" <ji...@apache.org> on 2018/10/23 07:41:00 UTC

[jira] [Created] (CALCITE-2636) SQL parser has quadratic running time when SQL string is very large

Julian Hyde created CALCITE-2636:
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             Summary: SQL parser has quadratic running time when SQL string is very large
                 Key: CALCITE-2636
                 URL: https://issues.apache.org/jira/browse/CALCITE-2636
             Project: Calcite
          Issue Type: Bug
            Reporter: Julian Hyde
            Assignee: Julian Hyde


SQL parser has quadratic running time when SQL string is very large.

This is due to {{SimpleCharStream.ExpandBuff(boolean)}} increasing the buffer in increments of 2,048 (2k) chars. If the SQL string is, say, 1,024k characters, then it will re-alloc at size 2k, 4k, 6k, ...,  1023k, and each time copy the whole string.

This issue was discovered by [~gian].



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