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-rw-r--r--storage/federatedx/federatedx_pushdown.cc302
1 files changed, 302 insertions, 0 deletions
diff --git a/storage/federatedx/federatedx_pushdown.cc b/storage/federatedx/federatedx_pushdown.cc
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+++ b/storage/federatedx/federatedx_pushdown.cc
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+/*
+ Copyright (c) 2019, 2020, MariaDB
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; version 2 of the License.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
+
+/* !!! For inclusion into ha_federatedx.cc */
+
+
+/*
+ This is a quick a dirty implemention of the derived_handler and select_handler
+ interfaces to be used to push select queries and the queries specifying
+ derived tables into FEDERATEDX engine.
+ The functions
+ create_federatedx_derived_handler and
+ create_federatedx_select_handler
+ that return the corresponding interfaces for pushdown capabilities do
+ not check a lot of things. In particular they do not check that the tables
+ of the pushed queries belong to the same foreign server.
+
+ The implementation is provided purely for testing purposes.
+ The pushdown capabilities are enabled by turning on the plugin system
+ variable federated_pushdown:
+ set global federated_pushdown=1;
+*/
+
+
+static derived_handler*
+create_federatedx_derived_handler(THD* thd, TABLE_LIST *derived)
+{
+ if (!use_pushdown)
+ return 0;
+
+ ha_federatedx_derived_handler* handler = NULL;
+ handlerton *ht= 0;
+
+ SELECT_LEX_UNIT *unit= derived->derived;
+
+ for (SELECT_LEX *sl= unit->first_select(); sl; sl= sl->next_select())
+ {
+ if (!(sl->join))
+ return 0;
+ for (TABLE_LIST *tbl= sl->join->tables_list; tbl; tbl= tbl->next_local)
+ {
+ if (!tbl->table)
+ return 0;
+ if (!ht)
+ ht= tbl->table->file->partition_ht();
+ else if (ht != tbl->table->file->partition_ht())
+ return 0;
+ }
+ }
+
+ handler= new ha_federatedx_derived_handler(thd, derived);
+
+ return handler;
+}
+
+
+/*
+ Implementation class of the derived_handler interface for FEDERATEDX:
+ class implementation
+*/
+
+ha_federatedx_derived_handler::ha_federatedx_derived_handler(THD *thd,
+ TABLE_LIST *dt)
+ : derived_handler(thd, federatedx_hton),
+ share(NULL), txn(NULL), iop(NULL), stored_result(NULL)
+{
+ derived= dt;
+}
+
+ha_federatedx_derived_handler::~ha_federatedx_derived_handler() {}
+
+int ha_federatedx_derived_handler::init_scan()
+{
+ THD *thd;
+ int rc= 0;
+
+ DBUG_ENTER("ha_federatedx_derived_handler::init_scan");
+
+ TABLE *table= derived->get_first_table()->table;
+ ha_federatedx *h= (ha_federatedx *) table->file;
+ iop= &h->io;
+ share= get_share(table->s->table_name.str, table);
+ thd= table->in_use;
+ txn= h->get_txn(thd);
+ if ((rc= txn->acquire(share, thd, TRUE, iop)))
+ DBUG_RETURN(rc);
+
+ if ((*iop)->query(derived->derived_spec.str, derived->derived_spec.length))
+ goto err;
+
+ stored_result= (*iop)->store_result();
+ if (!stored_result)
+ goto err;
+
+ DBUG_RETURN(0);
+
+err:
+ DBUG_RETURN(HA_FEDERATEDX_ERROR_WITH_REMOTE_SYSTEM);
+}
+
+int ha_federatedx_derived_handler::next_row()
+{
+ int rc;
+ FEDERATEDX_IO_ROW *row;
+ ulong *lengths;
+ Field **field;
+ int column= 0;
+ Time_zone *saved_time_zone= table->in_use->variables.time_zone;
+ DBUG_ENTER("ha_federatedx_derived_handler::next_row");
+
+ if ((rc= txn->acquire(share, table->in_use, TRUE, iop)))
+ DBUG_RETURN(rc);
+
+ if (!(row= (*iop)->fetch_row(stored_result)))
+ DBUG_RETURN(HA_ERR_END_OF_FILE);
+
+ /* Convert row to internal format */
+ table->in_use->variables.time_zone= UTC;
+ lengths= (*iop)->fetch_lengths(stored_result);
+
+ for (field= table->field; *field; field++, column++)
+ {
+ if ((*iop)->is_column_null(row, column))
+ (*field)->set_null();
+ else
+ {
+ (*field)->set_notnull();
+ (*field)->store((*iop)->get_column_data(row, column),
+ lengths[column], &my_charset_bin);
+ }
+ }
+ table->in_use->variables.time_zone= saved_time_zone;
+
+ DBUG_RETURN(rc);
+}
+
+int ha_federatedx_derived_handler::end_scan()
+{
+ DBUG_ENTER("ha_federatedx_derived_handler::end_scan");
+
+ (*iop)->free_result(stored_result);
+
+ free_share(txn, share);
+
+ DBUG_RETURN(0);
+}
+
+void ha_federatedx_derived_handler::print_error(int, unsigned long)
+{
+}
+
+
+static select_handler*
+create_federatedx_select_handler(THD* thd, SELECT_LEX *sel)
+{
+ if (!use_pushdown)
+ return 0;
+
+ ha_federatedx_select_handler* handler = NULL;
+ handlerton *ht= 0;
+
+ for (TABLE_LIST *tbl= thd->lex->query_tables; tbl; tbl= tbl->next_global)
+ {
+ if (!tbl->table)
+ return 0;
+ if (!ht)
+ ht= tbl->table->file->partition_ht();
+ else if (ht != tbl->table->file->partition_ht())
+ return 0;
+ }
+
+ /*
+ Currently, ha_federatedx_select_handler::init_scan just takes the
+ thd->query and sends it to the backend.
+ This obviously won't work if the SELECT uses an "INTO @var" or
+ "INTO OUTFILE". It is also unlikely to work if the select has some
+ other kind of side effect.
+ */
+ if (sel->uncacheable & UNCACHEABLE_SIDEEFFECT)
+ return NULL;
+
+ handler= new ha_federatedx_select_handler(thd, sel);
+
+ return handler;
+}
+
+/*
+ Implementation class of the select_handler interface for FEDERATEDX:
+ class implementation
+*/
+
+ha_federatedx_select_handler::ha_federatedx_select_handler(THD *thd,
+ SELECT_LEX *sel)
+ : select_handler(thd, federatedx_hton),
+ share(NULL), txn(NULL), iop(NULL), stored_result(NULL)
+{
+ select= sel;
+}
+
+ha_federatedx_select_handler::~ha_federatedx_select_handler() {}
+
+int ha_federatedx_select_handler::init_scan()
+{
+ int rc= 0;
+
+ DBUG_ENTER("ha_federatedx_select_handler::init_scan");
+
+ TABLE *table= 0;
+ for (TABLE_LIST *tbl= thd->lex->query_tables; tbl; tbl= tbl->next_global)
+ {
+ if (!tbl->table)
+ continue;
+ table= tbl->table;
+ break;
+ }
+ ha_federatedx *h= (ha_federatedx *) table->file;
+ iop= &h->io;
+ share= get_share(table->s->table_name.str, table);
+ txn= h->get_txn(thd);
+ if ((rc= txn->acquire(share, thd, TRUE, iop)))
+ DBUG_RETURN(rc);
+
+ if ((*iop)->query(thd->query(), thd->query_length()))
+ goto err;
+
+ stored_result= (*iop)->store_result();
+ if (!stored_result)
+ goto err;
+
+ DBUG_RETURN(0);
+
+err:
+ DBUG_RETURN(HA_FEDERATEDX_ERROR_WITH_REMOTE_SYSTEM);
+}
+
+int ha_federatedx_select_handler::next_row()
+{
+ int rc= 0;
+ FEDERATEDX_IO_ROW *row;
+ ulong *lengths;
+ Field **field;
+ int column= 0;
+ Time_zone *saved_time_zone= table->in_use->variables.time_zone;
+ DBUG_ENTER("ha_federatedx_select_handler::next_row");
+
+ if ((rc= txn->acquire(share, table->in_use, TRUE, iop)))
+ DBUG_RETURN(rc);
+
+ if (!(row= (*iop)->fetch_row(stored_result)))
+ DBUG_RETURN(HA_ERR_END_OF_FILE);
+
+ /* Convert row to internal format */
+ table->in_use->variables.time_zone= UTC;
+ lengths= (*iop)->fetch_lengths(stored_result);
+
+ for (field= table->field; *field; field++, column++)
+ {
+ if ((*iop)->is_column_null(row, column))
+ (*field)->set_null();
+ else
+ {
+ (*field)->set_notnull();
+ (*field)->store((*iop)->get_column_data(row, column),
+ lengths[column], &my_charset_bin);
+ }
+ }
+ table->in_use->variables.time_zone= saved_time_zone;
+
+ DBUG_RETURN(rc);
+}
+
+int ha_federatedx_select_handler::end_scan()
+{
+ DBUG_ENTER("ha_federatedx_derived_handler::end_scan");
+
+ free_tmp_table(thd, table);
+ table= 0;
+
+ (*iop)->free_result(stored_result);
+
+ free_share(txn, share);
+
+ DBUG_RETURN(0);
+}
+
+void ha_federatedx_select_handler::print_error(int error, myf error_flag)
+{
+ select_handler::print_error(error, error_flag);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-09-13 11:44:10 +0000