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MWL#128: Added into EXPLAIN output info about types of the used join buffers and

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about the employed join algorithms.
Refactored constructors of the JOIN_CACHE* classes.
This commit is contained in:
Igor Babaev
2010-10-18 13:33:05 -07:00
parent 79087c9e07
commit 25f5debdc7
65 changed files with 1072 additions and 995 deletions
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48
sql/sql_join_cache.cc
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@@ -2372,6 +2372,54 @@ finish:
return rc;
}
/*
Add a comment on the join algorithm employed by the join cache
SYNOPSIS
print_explain_comment()
str string to add the comment on the employed join algorithm to
DESCRIPTION
This function adds info on the type of the used join buffer (flat or
incremental) and on the type of the the employed join algorithm (BNL,
BNLH, BKA or BKAH) to the the end of the sring str.
RETURN VALUE
none
*/
void JOIN_CACHE::print_explain_comment(String *str)
{
str->append(STRING_WITH_LEN(" ("));
const char *buffer_type= prev_cache ? "incremental" : "flat";
str->append(buffer_type);
str->append(STRING_WITH_LEN(", "));
const char *join_alg;
switch (get_join_alg()) {
case BNL_JOIN_ALG:
join_alg= "BNL";
break;
case BNLH_JOIN_ALG:
join_alg= "BNLH";
break;
case BKA_JOIN_ALG:
join_alg= "BKA";
break;
case BKAH_JOIN_ALG:
join_alg= "BKAH";
break;
default:
DBUG_ASSERT(0);
}
str->append(join_alg);
str->append(STRING_WITH_LEN(" join"));
str->append(STRING_WITH_LEN(")"));
}
/*
Initialize a hashed join cache