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Fix to bug #694, http://bugs.mariadb.com/show_bug.cgi?id=694

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query_classifier.cc: set_query_type lost previous query type if the new was more restrictive. Problem was that if query is both READ and SESSION_WRITE and configuration parameter use_sql_variables_in=all was set, routing target became ambiguous. Replaced call to set_query_type with simply adding new type to type (=bit field) and checking unsupported combinations in readwritesplit.c:get_route_target. If such a case is met, a detailed error is written to error log in readwritesplit.c. mysql_client.c sees the error code and sends an error to client. Then mysql_client.c calls router's handleError which ensures that there are enough backend servers so that the session can continue.
This commit is contained in:
VilhoRaatikka
2015-01-15 15:16:22 +02:00
parent b3824a1eaf
commit 39e4253c81
3 changed files with 95 additions and 37 deletions
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51
server/modules/routing/readwritesplit/readwritesplit.c
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@ -1368,8 +1368,27 @@ static route_target_t get_route_target (
QUERY_IS_TYPE(qtype, QUERY_TYPE_ENABLE_AUTOCOMMIT) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_DISABLE_AUTOCOMMIT))
{
/** hints don't affect on routing */
target = TARGET_ALL;
/**
* This is problematic query because it would be routed to all
* backends but since this is SELECT that is not possible:
* 1. response set is not handled correctly in clientReply and
* 2. multiple results can degrade performance.
*/
if (QUERY_IS_TYPE(qtype, QUERY_TYPE_READ))
{
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,
"Warning : The query can't be routed to all "
"backend servers because it includes SELECT and "
"SQL variable modifications which is not supported. "
"Set use_sql_variables_in=master or split the "
"query to two, where SQL variable modifications "
"are done in the first and the SELECT in the "
"second one.")));
target = TARGET_MASTER;
}
target |= TARGET_ALL;
}
/**
* Hints may affect on routing of the following queries
@ -2139,6 +2158,34 @@ static bool route_single_stmt(
if (TARGET_IS_ALL(route_target))
{
/** Multiple, conflicting routing target. Return error */
if (TARGET_IS_MASTER(route_target) ||
TARGET_IS_SLAVE(route_target))
{
char* query_str = modutil_get_query(querybuf);
char* qtype_str = skygw_get_qtype_str(qtype);
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,
"Error: Can't route %s:%s:\"%s\". SELECT with "
"session data modification is not supported "
"if configuration parameter "
"use_sql_variables_in=all .",
STRPACKETTYPE(packet_type),
qtype_str,
(query_str == NULL ? "(empty)" : query_str))));
LOGIF(LT, (skygw_log_write(LOGFILE_TRACE,
"Unable to route the query "
"without losing session data "
"modification from other "
"servers. <")));
if (query_str) free (query_str);
if (qtype_str) free(qtype_str);
succp = false;
goto retblock;
}
/**
* It is not sure if the session command in question requires
* response. Statement is examined in route_session_write.