[tarantool-patches] Re: [PATCH 2/2] sql: rework 'DROP INDEX' and 'DROP TABLE' handling
n.pettik
korablev at tarantool.org
Wed Apr 4 21:11:29 MSK 2018
> On 3 Apr 2018, at 21:27, Vladislav Shpilevoy <v.shpilevoy at tarantool.org> wrote:
>
> See 6 comments below.
>
> 03.04.2018 19:14, Nikita Pettik пишет:
>> As a part of SQL data dictionary integration, 'DROP INDEX' and
>> 'DROP TABLE' statements proccessing has been refactored in order
>> to avoid using SQL specific internal structures.
>> However, triggers still aren't transfered to server, so to drop them
>> it is required to lookup SQL table and emit apporpriate opcodes.
>> Also, added comments and fixed codestyle for functions processing
>> 'DROP' routine.
>>
>> Part of #3222.
>> ---
>> src/box/sql/build.c | 241 ++++++++++++++++++++++++++----------------------
>> src/box/sql/parse.c | 6 +-
>> src/box/sql/parse.y | 6 +-
>> src/box/sql/sqliteInt.h | 6 +-
>> 4 files changed, 140 insertions(+), 119 deletions(-)
>>
>> diff --git a/src/box/sql/build.c b/src/box/sql/build.c
>> index 61194e06b..219cc974b 100644
>> --- a/src/box/sql/build.c
>> +++ b/src/box/sql/build.c
>> @@ -46,6 +46,7 @@
>> #include "sqliteInt.h"
>> #include "vdbeInt.h"
>> #include "tarantoolInt.h"
>> +#include "box/box.h"
>> #include "box/sequence.h"
>> #include "box/session.h"
>> #include "box/identifier.h"
>> @@ -2152,48 +2153,50 @@ sql_clear_stat_spaces(Parse * pParse, const char *zType, const char *zName)
>> zType, zName);
>> }
>> -/*
>> +/**
>> * Generate code to drop a table.
>> + * This routine includes dropping triggers, sequences,
>> + * all indexes and entry from _space space.
>> + *
>> + * @param parse_context Current parsing context.
>> + * @param space Space to be dropped.
>> + * @param is_view True, if space is
>> */
>> static void
>> -sqlite3CodeDropTable(Parse * pParse, Table * pTab, int isView)
>> +sql_code_drop_table(struct Parse *parse_context, struct space *space,
>> + bool is_view)
>> {
>> - Vdbe *v;
>> - sqlite3 *db = pParse->db;
>> - Trigger *pTrigger;
>> -
>> - v = sqlite3GetVdbe(pParse);
>>
>> + struct sqlite3 *db = parse_context->db;
>> + struct Vdbe *v = sqlite3GetVdbe(parse_context);
>> assert(v != 0);
> 1. Lets in all new code use explicit ==/!= NULL.
Fixed:
- assert(v != 0);
+ assert(v != NULL);
>> /*
>> * Drop all triggers associated with the table being
>> * dropped. Code is generated to remove entries from
>> * _trigger. OP_DropTrigger will remove it from internal
>> * SQL structures.
>> - */
>> - pTrigger = pTab->pTrigger;
>> - /* Do not account triggers deletion - they will be accounted
>> + *
>> + * Do not account triggers deletion - they will be accounted
> 2. Out of 66.
Fixed:
- * Do not account triggers deletion - they will be accounted
- * in DELETE from _space below.
+ * Do not account triggers deletion - they will be
+ * accounted in DELETE from _space below.
>> @@ -2214,7 +2216,7 @@ sqlite3CodeDropTable(Parse * pParse, Table * pTab, int isView)
>> * Drop all _space and _index entries that refer to the
>> * table.
>> */
>> - if (!isView) {
>> + if (!is_view) {
> 3. I looked at the indexes deletion more carefully and noticed, that you can avoid any allocations
> here. Why can not you just walk through space->index array and generate OP_SDelete opcodes for
> each index, starting from 1 (to skip primary)? AFAIK the entire index array is not changed until you
> reach VdbeExec, so you can do not save index identifiers on region to generate opcodes.
IDK why I didn’t do it in this way (probably due to my ‘paranoia’).
Reworked:
- uint32_t *iids =
- (uint32_t *) region_alloc(&fiber()->gc,
- sizeof(uint32_t) *
- (index_count - 1));
- /* Save index ids to be deleted except for PK. */
for (uint32_t i = 1; i < index_count; ++i) {
- iids[i - 1] = space->index[i]->def->iid;
- }
- for (uint32_t i = 0; i < index_count - 1; ++i) {
- sqlite3VdbeAddOp2(v, OP_Integer, iids[i],
+ sqlite3VdbeAddOp2(v, OP_Integer,
+ space->index[i]->def->iid,
space_id_reg + 1);
sqlite3VdbeAddOp3(v, OP_MakeRecord,
space_id_reg, 2, idx_rec_reg);
@@ -2233,7 +2226,7 @@ sql_code_drop_table(struct Parse *parse_context, struct space *space,
idx_rec_reg);
VdbeComment((v,
"Remove secondary index iid = %u",
- iids[i]));
+ space->index[i]->def->iid));
>> uint32_t index_count = space->index_count;
>> if (index_count > 1) {
>> /*
>> @@ -2257,71 +2259,78 @@ sqlite3CodeDropTable(Parse * pParse, Table * pTab, int isView)
>> sqlite3VdbeAddOp2(v, OP_SDelete, BOX_SPACE_ID, idx_rec_reg);
>> sqlite3VdbeChangeP5(v, OPFLAG_NCHANGE);
>> VdbeComment((v, "Delete entry from _space"));
>> - /* Remove the table entry from SQLite's internal schema and modify
>> - * the schema cookie.
>> + /*
>> + * Remove the table entry from SQLite's internal schema
>> + * and modify the schema cookie.
>> */
> 4. But you have deleted cookie updates in the previous commit. Source code of OP_DropTable and all
> called there functions does not contain cookie changes.
Removed obsolete comment:
- /*
- * Remove the table entry from SQLite's internal schema
- * and modify the schema cookie.
- */
+ /* Remove the table entry from SQLite's internal schema. */
>> + sqlite3VdbeAddOp4(v, OP_DropTable, 0, 0, 0, space->def->name, 0);
>> - sqlite3VdbeAddOp4(v, OP_DropTable, 0, 0, 0, pTab->zName, 0);
>> -
>> - /* FIXME: DDL is impossible inside a transaction so far.
>> + /*
>> * Replace to _space/_index will fail if active
>> * transaction. So, don't pretend, that we are able to
>> * anything back. To be fixed when transactions
>> * DDL are enabled.
>> */
>> - /* sqlite3ChangeCookie(pParse); */
>> sqliteViewResetAll(db);
>> }
>> -/*
>> +/**
>> * This routine is called to do the work of a DROP TABLE statement.
>> - * pName is the name of the table to be dropped.
>> + *
>> + * @param parse_context Current parsing context.
>> + * @param table_name_list List containing table name.
>> + * @param is_view True, if statement is really 'DROP VIEW'.
>> + * @param if_exists True, if statement contains 'IF EXISTS' clause.
>> */
>> void
>> -sqlite3DropTable(Parse * pParse, SrcList * pName, int isView, int noErr)
>> +sql_drop_table(struct Parse *parse_context, struct SrcList *table_name_list,
>> + bool is_view, bool if_exists)
>> {
>> - Table *pTab;
>> - Vdbe *v = sqlite3GetVdbe(pParse);
>> - sqlite3 *db = pParse->db;
>> -
>> + struct Vdbe *v = sqlite3GetVdbe(parse_context);
>> + struct sqlite3 *db = parse_context->db;
>> if (v == NULL || db->mallocFailed) {
>> goto exit_drop_table;
>> }
>> - /* Activate changes counting here to account
>> + /*
>> + * Activate changes counting here to account
>> * DROP TABLE IF NOT EXISTS, if the table really does not
>> * exist.
>> */
>> - if (!pParse->nested)
>> + if (!parse_context->nested)
> 5. Please, use explicit != 0. Why you use !int, the variable seems to be boolean. It slightly confuses.
This this not != check, but vice versa == 0 check.
! In this case would better fit, wouldn’t it?
(Since any number except for 0 would be converted to false)
>> sqlite3VdbeCountChanges(v);
>> - assert(pParse->nErr == 0);
>> - assert(pName->nSrc == 1);
>> - assert(db->pSchema != NULL);
>> - if (noErr)
>> - db->suppressErr++;
>> - assert(isView == 0 || isView == LOCATE_VIEW);
>> - pTab = sqlite3LocateTable(pParse, isView, pName->a[0].zName);
>> - if (noErr)
>> - db->suppressErr--;
>> -
>> - if (pTab == 0)
>> + assert(parse_context->nErr == 0);
>> + assert(table_name_list->nSrc == 1);
>> + assert(is_view == 0 || is_view == LOCATE_VIEW);
>> + const char *space_name = table_name_list->a[0].zName;
>> + uint32_t space_id = box_space_id_by_name(space_name,
>> + strlen(space_name));
>> + if (space_id == BOX_ID_NIL) {
>> + if (!is_view && !if_exists)
>> + sqlite3ErrorMsg(parse_context, "no such table: %s",
>> + space_name);
>> + if (is_view && !if_exists)
>> + sqlite3ErrorMsg(parse_context, "no such view: %s",
>> + space_name);
>> goto exit_drop_table;
>> -#ifndef SQLITE_OMIT_VIEW
>> - /* Ensure DROP TABLE is not used on a view, and DROP VIEW is not used
>> - * on a table.
>> + }
>> + struct space *space = space_by_id(space_id);
>> + assert(space != NULL);
>> + /*
>> + * Ensure DROP TABLE is not used on a view,
>> + * and DROP VIEW is not used on a table.
>> */
>> - if (isView && !space_is_view(pTab)) {
>> - sqlite3ErrorMsg(pParse, "use DROP TABLE to delete table %s",
>> - pTab->zName);
>> + if (is_view && !space->def->opts.is_view) {
>> + sqlite3ErrorMsg(parse_context, "use DROP TABLE to delete table %s",
>> + space_name);
>> goto exit_drop_table;
>> }
>> - if (!isView && space_is_view(pTab)) {
>> - sqlite3ErrorMsg(pParse, "use DROP VIEW to delete view %s",
>> - pTab->zName);
>> + if (!is_view && space->def->opts.is_view) {
>> + sqlite3ErrorMsg(parse_context, "use DROP VIEW to delete view %s",
>> + space_name);
>> goto exit_drop_table;
>> }
>> -#endif
>> -
>> - /* Generate code to remove the table from Tarantool and internal SQL
>> + /*
>> + * Generate code to remove the table from Tarantool and internal SQL
> 6. Out of 66.
Fixed whole comment (to fit into 66 chars):
- * Generate code to remove the table from Tarantool and internal SQL
- * tables. Basically, it consists from 3 stages:
- * 1. Delete statistics from _stat1 and _stat4 tables (if any exist)
- * 2. In case of presence of FK constraints, i.e. current table is child
- * or parent, then start new transaction and erase from table
- * all data row by row. On each deletion check whether any FK
- * violations have occurred. If ones take place, then rollback
- * transaction and halt VDBE. Otherwise, commit transaction.
- * 3. Drop table by truncating (if step 2 was skipped), removing
- * indexes from _index table and eventually tuple with corresponding
- * space_id from _space.
+ * Generate code to remove the table from Tarantool
+ * and internal SQL tables. Basically, it consists
+ * from 3 stages:
+ * 1. Delete statistics from _stat1 and _stat4 tables.
+ * 2. In case of presence of FK constraints, i.e. current
+ * table is child or parent, then start new transaction
+ * and erase from table all data row by row. On each
+ * deletion check whether any FK violations have
+ * occurred. If ones take place, then rollback
+ * transaction and halt VDBE.
+ * 3. Drop table by truncating (if step 2 was skipped),
+ * removing indexes from _index space and eventually
+ * tuple with corresponding space_id from _space.
*/
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