Parallel queries on unixODBC are not working

Odbc Thread level should be set:      

/*
 * use just one mutex for all the lists, this avoids any issues
 * with deadlocks, the performance issue should be minimal, if it
 * turns out to be a problem, we can readdress this
 *
 * We also have a mutex to protect the connection pooling code
 *
 * If compiled with thread support the DM allows four different
 * thread strategies
 *
 * Level 0 - Only the DM internal structures are protected
 * the driver is assumed to take care of it's self
 *
 * Level 1 - The driver is protected down to the statement level
 * each statement will be protected, and the same for the connect
 * level for connect functions, note that descriptors are considered
 * equal to statements when it comes to thread protection.
 *
 * Level 2 - The driver is protected at the connection level. only
 * one thread can be in a particular driver at one time
 *
 * Level 3 - The driver is protected at the env level, only one thing
 * at a time.
 *
 * By default the driver open connections with a lock level of 3,
 * this can be changed by adding the line
 *
 * Threading = N
 *
 * to the driver entry in odbcinst.ini, where N is the locking level
 * (0-3)
 *
 */

See
http://stackoverflow.com/questions/4207458/using-unixodbc-in-a-multithreaded-concurrent-setting

Recommended UnixODBC settings for postgres 

[postgresql]

Description = General ODBC for PostgreSQL
Driver      = /usr/lib64/libodbcpsql.so
Setup       = /usr/lib64/libodbcpsqlS.so
FileUsage   = 1
# Since 1.6 if the driver manager was built with thread support you may add another entry to each driver entry.
# This entry alters the default thread serialization level.
Threading   = 2

https://support.zabbix.com/browse/ZBX-6839