Uploaded image for project: 'Phoenix'
  1. Phoenix
  2. PHOENIX-3023

Slow performance when limit queries are executed in parallel by default

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 4.8.0
    • Fix Version/s: 4.8.0
    • Labels:
      None

      Description

      After this commit, limit queries are executed in parallel which causes performance to be ~5-10x slower. Providing a serial hint fixes it though.

      After commit:

      select * from WIDE_PK order by mypk DESC limit 1; // this takes ~400ms
      
      CLIENT 1280-CHUNK 1996304 ROWS 6380181208 BYTES PARALLEL 4-WAY REVERSE FULL SCAN OVER WIDE_PK SERVER 1 ROW LIMIT CLIENT MERGE SORT CLIENT 1 ROW LIMIT
      

      Before commit:

      select * from WIDE_PK order by mypk DESC limit 1; // this takes ~40ms
      
      CLIENT 1280-CHUNK 1996304 ROWS 6380181208 BYTES SERIAL 4-WAY REVERSE FULL SCAN OVER WIDE_PK SERVER 1 ROW LIMIT CLIENT MERGE SORT CLIENT 1 ROW LIMIT
      

      Test was done on a single node machine running HBase 0.98.17. DDL used was

      CREATE TABLE WIDE_PK (MYPK CHAR(500) NOT NULL PRIMARY KEY,CF.column1 INTEGER,CF.column2 INTEGER,CF.column3 INTEGER,CF.column4 INTEGER,CF.column5 INTEGER) SALT_BUCKETS=4 with phoenix.stats.guidepost.width of 5000000
      

        Attachments

        1. PHOENIX-3023.patch
          18 kB
          Samarth Jain
        2. PHOENIX-3023_v2.patch
          20 kB
          Samarth Jain

          Activity

            People

            • Assignee:
              samarthjain Samarth Jain
              Reporter:
              mujtabachohan Mujtaba Chohan
            • Votes:
              0 Vote for this issue
              Watchers:
              5 Start watching this issue

              Dates

              • Created:
                Updated:
                Resolved: