[CALCITE-1211] limit > 7 on the Cassandra Adapter switches to EnumerableLimit rule

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.7.0
• Fix Version/s: 1.8.0
• Component/s: cassandra-adapter
• Assignee: Michael Mior
• Reporter: Dan Di Spaltro
• Created: 21/Apr/16 07:17
• Updated: 09/Dec/17 18:34
• Resolved: 22/Apr/16 14:03

Description

I copied the testProject query because I was noticing a EnumerableLimit showing up on explains when a limit was higher than `1`. So I narrowed it down to 7, anything above 7 and the plan looks like this

Plan after physical tweaks: EnumerableLimit(fetch=[8]): rowcount = 8.0, cumulative cost = {112.5 rows, 122.0 cpu, 0.0 io}, id = 2083
  CassandraToEnumerableConverter: rowcount = 15.0, cumulative cost = {104.5 rows, 114.0 cpu, 0.0 io}, id = 2081
    CassandraProject(tweet_id=[$2]): rowcount = 15.0, cumulative cost = {103.0 rows, 112.5 cpu, 0.0 io}, id = 2079
      CassandraFilter(condition=[=(CAST($0):CHAR(8) CHARACTER SET "ISO-8859-1" COLLATE "ISO-8859-1$en_US$primary", '!PUBLIC!')]): rowcount = 15.0, cumulative cost = {101.5 rows, 111.0 cpu, 0.0 io}, id = 2077
        CassandraTableScan(table=[[twissandra, userline]]): rowcount = 100.0, cumulative cost = {100.0 rows, 101.0 cpu, 0.0 io}, id = 1915

anything 7 or below looks like this

CassandraToEnumerableConverter: rowcount = 7.0, cumulative cost = {111.07282262603232 rows, 112.75 cpu, 0.0 io}, id = 2257
  CassandraProject(tweet_id=[$2]): rowcount = 7.0, cumulative cost = {110.37282262603232 rows, 112.05 cpu, 0.0 io}, id = 2255
    CassandraSort(fetch=[7]): rowcount = 7.0, cumulative cost = {109.67282262603231 rows, 111.35 cpu, 0.0 io}, id = 2253
      CassandraFilter(condition=[=(CAST($0):CHAR(8) CHARACTER SET "ISO-8859-1" COLLATE "ISO-8859-1$en_US$primary", '!PUBLIC!')]): rowcount = 15.0, cumulative cost = {101.5 rows, 111.0 cpu, 0.0 io}, id = 2251
        CassandraTableScan(table=[[twissandra, userline]]): rowcount = 100.0, cumulative cost = {100.0 rows, 101.0 cpu, 0.0 io}, id = 2089

If I wanted to change that would I alter the cost of the sort rule?