From: "n.pettik" <korablev@tarantool.org> To: tarantool-patches@freelists.org Cc: Kirill Shcherbatov <kshcherbatov@tarantool.org> Subject: [tarantool-patches] Re: [PATCH v2 4/8] sql: get rid of SQL_FUNC_COUNT flag Date: Tue, 13 Aug 2019 23:35:36 +0300 [thread overview] Message-ID: <EAD66280-1CF2-4AE4-87BA-E81B3A067D6E@tarantool.org> (raw) In-Reply-To: <2f18c9df1d818a222f2fb3005d13bd59228d4698.1565275469.git.kshcherbatov@tarantool.org> > On 8 Aug 2019, at 17:50, Kirill Shcherbatov <kshcherbatov@tarantool.org> wrote: > > Tarantool's SQL engine generates a different VDBE bytecode > for ..COUNT(*).. and ..COUNT(fieldname).. operations: > the first one produces a lightweight OP_Count operation that uses > native mechanism to report the count of record in index while > the second one pessimistically opens a space read iterator and > uses Count aggregate function. > > A helper routine is_simple_count decides whether such > optimisation is correct. Using SQL_FUNC_COUNT flag to mark a > dummy (non-functional) Why do you consider it to be non-functional? > function entry with 0 arguments is a bad practice Why? Please, support this with arguments. As I understand, the real reason is that we are striving to remove function overloading, isn’t it? > and should be reworked in relation with introducing > a uniform functions cache in further patches. > > Therefore SQL_FUNC_COUNT flag test in is_simple_count helper > was replaced with more straightforward test with manually looking > for count of function arguments passed. > > Needed for #2200, #4113, #2233 > --- > > - if ((agg_info->aFunc[0].pFunc->funcFlags & SQL_FUNC_COUNT) == 0) > + if (agg_info->aFunc->pExpr->x.pList != NULL && > + agg_info->aFunc->pExpr->x.pList->nExpr > 0) > return NULL; Hm, this code works just by accident :) There’s no check that function is really COUNT, but we are lucky enough and there’s no other aggregate function which can take empty list of arguments... > if (expr->flags & EP_Distinct) > return NULL; > -- > 2.22.0
next prev parent reply other threads:[~2019-08-13 20:35 UTC|newest] Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-08-08 14:50 [tarantool-patches] [PATCH v2 0/8] sql: uniform SQL and Lua functions subsystem Kirill Shcherbatov 2019-08-08 14:50 ` [tarantool-patches] [PATCH v2 1/8] sql: remove SQL_PreferBuiltin flag Kirill Shcherbatov 2019-08-09 16:07 ` [tarantool-patches] " n.pettik 2019-08-12 21:58 ` Konstantin Osipov 2019-08-08 14:50 ` [tarantool-patches] [PATCH v2 2/8] sql: GREATEST, LEAST instead of MIN/MAX overload Kirill Shcherbatov 2019-08-09 17:37 ` [tarantool-patches] " n.pettik 2019-08-13 8:26 ` Kirill Shcherbatov 2019-08-12 21:59 ` Konstantin Osipov 2019-08-08 14:50 ` [tarantool-patches] [PATCH v2 3/8] sql: wrap all trim functions in dispatcher Kirill Shcherbatov 2019-08-09 18:05 ` [tarantool-patches] " n.pettik 2019-08-13 8:28 ` Kirill Shcherbatov 2019-08-13 22:19 ` n.pettik 2019-08-12 22:00 ` Konstantin Osipov 2019-08-08 14:50 ` [tarantool-patches] [PATCH v2 4/8] sql: get rid of SQL_FUNC_COUNT flag Kirill Shcherbatov 2019-08-12 22:01 ` [tarantool-patches] " Konstantin Osipov 2019-08-13 20:35 ` n.pettik [this message] 2019-08-14 7:25 ` Kirill Shcherbatov 2019-08-08 14:50 ` [tarantool-patches] [PATCH v2 5/8] sql: introduce a signature_mask for functions Kirill Shcherbatov 2019-08-12 22:04 ` [tarantool-patches] " Konstantin Osipov 2019-08-13 8:32 ` Kirill Shcherbatov 2019-08-13 8:44 ` Konstantin Osipov 2019-08-13 20:38 ` n.pettik 2019-08-14 7:21 ` Kirill Shcherbatov 2019-08-08 14:50 ` [tarantool-patches] [PATCH v2 6/8] sql: rename OP_Function to OP_BuiltinFunction Kirill Shcherbatov 2019-08-12 22:04 ` [tarantool-patches] " Konstantin Osipov 2019-08-13 20:36 ` n.pettik 2019-08-08 14:50 ` [tarantool-patches] [PATCH v2 7/8] sql: get rid of FuncDef function hash Kirill Shcherbatov 2019-08-12 22:11 ` [tarantool-patches] " Konstantin Osipov 2019-08-13 7:29 ` Kirill Shcherbatov 2019-08-13 8:42 ` Konstantin Osipov 2019-08-13 9:45 ` Kirill Shcherbatov 2019-08-13 20:40 ` n.pettik 2019-08-16 12:57 ` Kirill Shcherbatov 2019-08-20 16:06 ` n.pettik 2019-08-08 14:50 ` [tarantool-patches] [PATCH v2 8/8] box: get rid of box.internal.sql_function_create Kirill Shcherbatov 2019-08-13 20:43 ` [tarantool-patches] " n.pettik 2019-08-16 12:57 ` Kirill Shcherbatov 2019-08-20 19:36 ` n.pettik
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=EAD66280-1CF2-4AE4-87BA-E81B3A067D6E@tarantool.org \ --to=korablev@tarantool.org \ --cc=kshcherbatov@tarantool.org \ --cc=tarantool-patches@freelists.org \ --subject='[tarantool-patches] Re: [PATCH v2 4/8] sql: get rid of SQL_FUNC_COUNT flag' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox