# ==== Purpose ==== # # Execute a statement and compute the number of rows of the result set. # # This is intended to be used for queries like SHOW BINLOG EVENTS # where you cannot use COUNT(*). It would be nicer if mysqltest had # this feature. Now we have to execute the statement several times and # see if 'query_get_value(*, row) returns 'No such row'. Beware to not # use this for queries that have side effects. # # ==== Usage ==== # # --let $statement= STATEMENT # --let $column= COLUMN_NAME # --source include/get_row_count.inc # --echo $statement has $row_count rows # # Parameters: # $statement # The statement to execute. Beware that this will be executed # multiple times. # # $column # The name of one column of the result. This may seem redundant # but unfortunately mysqltest forces you to specify a column name. # # Return value: # $row_count # The number of rows is stored in this variable. # Find upper bound on number of rows: check row numbers 1, 2, 4, 8, etc --let $_grc_max_row= 0 --let $_grc_min_row= 0 --let $_grc_row= 1 while ($_grc_max_row == 0) { if ($rpl_debug) { --echo row=$_grc_row min_row=$_grc_min_row max_row=$_grc_max_row } --let $_grc_result= query_get_value($statement, $column, $_grc_row) if ($_grc_result == 'No such row') { --let $_grc_max_row= $_grc_row } if ($_grc_result != 'No such row') { --let $_grc_min_row= $_grc_row --let $_grc_row= `SELECT $_grc_row * 2` } } # Binary search to find exact count. while (`SELECT $_grc_min_row + 1 < $_grc_max_row`) { if ($rpl_debug) { --echo row=$_grc_row min_row=$_grc_min_row max_row=$_grc_max_row } --let $_grc_row= `SELECT ($_grc_min_row + $_grc_max_row) DIV 2` --let $_grc_result= query_get_value($statement, $column, $_grc_row) if ($_grc_result == 'No such row') { --let $_grc_max_row= $_grc_row } if ($_grc_result != 'No such row') { --let $_grc_min_row= $_grc_row } } # Store result --let $row_count= $_grc_min_row