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Note, Oracle supports not only concatenation in the pattern,
but also additive and multiplicative expressions, e.g.:
SELECT 'x' FROM DUAL WHERE '100' LIKE 10*10;
This kind of expressions currently also do not work.
I think that in this rule:
| bit_expr LIKE mysql_concatenation_expr opt_escape
$$= new (thd->mem_root) Item_func_like(thd, $1, $3, $4,
if (unlikely($$ == NULL))
mysql_concatenation_expr should be just replaced to bit_expr.
But this adds a lot of new shift/reduce conflicts because of flaws in
the current grammar. They need to be fixed before MDEV-17359.
I reported these conflicts in:
MDEV-17374 Shift/reduce conflicts because of SOUNDS_SYM, ESCAPE_SYM,
USER_SYM not given precedence
I'll have a patch soon, then will return to MDEV-17359.
On 10/04/2018 09:26 AM, Alexander Barkov wrote:
> Can you please wait. I'll do some more analysis on the subject.
> On 10/04/2018 09:16 AM, Alexander Barkov wrote:
>> Hello Jerome,
>> On 10/03/2018 05:33 PM, jerome brauge wrote:
>>> Hello Alexander,
>>> Can you review this patch for MDEV-17359 ?
>>> Best regards.
>> Thanks for you contribution!
>> I noticed that Oracle also supports concatenation in the ESCAPE clause:
>> SELECT 'x' FROM DUAL WHERE 'a' LIKE 'b' ESCAPE ''||'x'||'';
>> This can be done separately, or can be addressed in the same patch, if
>> you wish :)
>> Review comments:
>> I've been trying to gradually make the two *.yy files as similar as
>> possible, to turn them into a single *.yy at the end.
>> So new changes in the grammar should usually make the two files look
>> more similar rather than make them diverge.
>> However, it seems in case of concatenation and like, having
>> only a pair of MYSQL_CONCAT_SYM and ORACLE_CONCAT_SYM does
>> not solve the problem. I could not make a quick patch which would
>> converge sql_yacc.yy and sql_yacc_ora.yy.
>> It's likely that we'll have to introduce separate MYSQL_LIKE_SYM
>> and ORACLE_LIKE_SYM. But I can do it separately later (after more
>> I the meanwhile, could you please rename mysql_concatenation_expr
>> into oracle_concatenation_expr in sql_yacc_ora.yy, so it looks
>> like this:
>> | oracle_concatenation_expr ORACLE_CONCAT_SYM simple_expr
>> $$= new (thd->mem_root)
>> Item_func_concat_operator_oracle(thd, $1, $3);
>> if (unlikely($$ == NULL))
>> Later, when we join the two *.yy files, we will need both
>> mysql_concatenation_expr (in its current reduction)
>> and oracle_concatenation_expr (in your reduction with
>> ORACLE_CONCAT_SYM and Item_func_concat_operator_oracle) .