Commit 8ff8fac5 authored by unknown's avatar unknown
Browse files

BUG#12915: post-review fixes

parent 1fe423ae

sql/opt_range.cc

+7 −5
Original line number Diff line number Diff line
@@ -584,8 +584,7 @@ SEL_ARG *SEL_ARG::clone_tree() 




/*

  Find an index that allows to retrieve first #limit records in the given

  order cheaper then one would retrieve them using full table scan.

  Find the best index to retrieve first N records in given order



  SYNOPSIS

    get_index_for_order()
@@ -594,10 +593,13 @@ SEL_ARG *SEL_ARG::clone_tree() 
      limit  Number of records that will be retrieved



  DESCRIPTION

    Find the best index that allows to retrieve first #limit records in the 

    given order cheaper then one would retrieve them using full table scan.



  IMPLEMENTATION

    Run through all table indexes and find the shortest index that allows

    records to be retrieved in given order. If there is such index and

    reading first #limit records from it is cheaper then scanning the entire

    table, return it.

    records to be retrieved in given order. We look for the shortest index

    as we will have fewer index pages to read with it.



    This function is used only by UPDATE/DELETE, so we take into account how

    the UPDATE/DELETE code will work:

sql/records.cc

+11 −8
Original line number Diff line number Diff line
@@ -235,13 +235,16 @@ static int rr_quick(READ_RECORD *info) 




/*

  Read next index record. The calling convention of this function is 

  compatible with READ_RECORD::read_record.

  A READ_RECORD::read_record implementation that reads index sequentially



  SYNOPSIS

    rr_index()

      info  Scan info

  

  DESCRIPTION

    Read the next index record (in forward direction) and translate return

    value.

    

  RETURN

    0   Ok

    -1  End of records