Send down a snasphot before sending bind parameters
Send down a snasphot before sending bind parameters

When a connection is reused by coordinator to execute other commands, global
snapshot at the datanode is reset. So we must send back the snapshot again
associated with the previous command. Without the fix, a query which requires
datanode access from multiple places would fail. For example, "SELECT p.name,
name(p.hobbies) FROM person* p ORDER BY 1,2;" from misc.sql was failing without
the patch

ovr/postgres-xl,Postgres-XL/Postgres-XL,Postgres-XL/Postgres-XL,oberstet/postgres-xl,techdragon/Postgres-XL,Postgres-XL/Postgres-XL,zeroae/postgres-xl,ovr/postgres-xl,pavanvd/postgres-xl,oberstet/postgres-xl,techdragon/Postgres-XL,yazun/postgres-xl,yazun/postgres-xl,oberstet/postgres-xl,techdragon/Postgres-XL,ovr/postgres-xl,zeroae/postgres-xl,zeroae/postgres-xl,ovr/postgres-xl,zeroae/postgres-xl,zeroae/postgres-xl,ovr/postgres-xl,techdragon/Postgres-XL,yazun/postgres-xl,pavanvd/postgres-xl,oberstet/postgres-xl,oberstet/postgres-xl,Postgres-XL/Postgres-XL,pavanvd/postgres-xl,Postgres-XL/Postgres-XL,pavanvd/postgres-xl,yazun/postgres-xl,yazun/postgres-xl,pavanvd/postgres-xl,techdragon/Postgres-XL