From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 07075215FF for ; Mon, 25 Feb 2019 07:58:38 -0500 (EST) Received: from turing.freelists.org ([127.0.0.1]) by localhost (turing.freelists.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id F3Y7CO51BYrm for ; Mon, 25 Feb 2019 07:58:37 -0500 (EST) Received: from smtpng2.m.smailru.net (smtpng2.m.smailru.net [94.100.179.3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTPS id B6FD621589 for ; Mon, 25 Feb 2019 07:58:37 -0500 (EST) Subject: [tarantool-patches] Re: [PATCH 1/2] sql: derive collation for built-in functions References: From: Vladislav Shpilevoy Message-ID: <92715853-76c0-36ca-1bae-84a8a8939f7e@tarantool.org> Date: Mon, 25 Feb 2019 15:58:35 +0300 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: tarantool-patches-bounce@freelists.org Errors-to: tarantool-patches-bounce@freelists.org Reply-To: tarantool-patches@freelists.org List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: tarantool-patches List-subscribe: List-owner: List-post: List-archive: To: tarantool-patches@freelists.org, Nikita Pettik Hi! Thanks for the patch! On 21/02/2019 21:01, Nikita Pettik wrote: > Functions such as trim(), substr() etc should return result with > collation derived from their arguments. So, lets add flag indicating > that collation of first argument must be applied to function's result to > SQL function definition. Using this flag, we can derive appropriate > collation in sql_expr_coll(). > > Part of #3932 > --- > src/box/sql/analyze.c | 6 +++--- > src/box/sql/expr.c | 23 +++++++++++++++++++++++ > src/box/sql/func.c | 22 +++++++++++----------- > src/box/sql/sqlInt.h | 31 +++++++++++++++++++++++-------- > test/sql/collation.result | 28 ++++++++++++++++++++++++++++ > test/sql/collation.test.lua | 11 +++++++++++ > 6 files changed, 99 insertions(+), 22 deletions(-) > > diff --git a/src/box/sql/sqlInt.h b/src/box/sql/sqlInt.h > index 2830ab639..5fb7285d8 100644 > --- a/src/box/sql/sqlInt.h > +++ b/src/box/sql/sqlInt.h > @@ -1633,6 +1633,13 @@ struct FuncDef { > } u; > /* Return type. */ > enum field_type ret_type; > + /** > + * If function returns string, it may require collation > + * to be applied on its result. For instance, result of > + * substr() built-in function must have the same collation > + * as its first argument. > + */ > + bool is_coll_derived; > }; This way works only for builtin functions taking not a bind parameter ('?'). For user-defined functions and for bind parameters it does not fit. How can you determine a function's result collation, if it is not builtin, and does not depend on arguments? Does SQL standard allow to define user functions without a runtime defined collation? If SQL standard does not define SQL functions at all, then what other vendors do with that problem?