[GitHub] [shardingsphere] azexcy commented on pull request #24075: Refactor DATA_MATCH consistency check by one query

["azexcy (via GitHub)" <gi...@apache.org>]

azexcy commented on PR #24075:
URL: https://github.com/apache/shardingsphere/pull/24075#issuecomment-1423914317

   MySQL and PostgreSQL streaming query
   Streaming queries in mysql and postgresql are different
   
   ```
       /**
        * We only stream result sets when they are forward-only, read-only, and the
        * fetch size has been set to Integer.MIN_VALUE
        * 
        * @return true if this result set should be streamed row at-a-time, rather
        *         than read all at once.
        */
       protected boolean createStreamingResultSet() {
           return ((this.resultSetType == java.sql.ResultSet.TYPE_FORWARD_ONLY) && (this.resultSetConcurrency == java.sql.ResultSet.CONCUR_READ_ONLY)
                   && (this.fetchSize == Integer.MIN_VALUE));
       }
   ```
   
   PostgreSQL
   ```
       // Enable cursor-based resultset if possible.
       if (fetchSize > 0 && !wantsScrollableResultSet() && !connection.getAutoCommit()
           && !wantsHoldableResultSet()) {
         flags |= QueryExecutor.QUERY_FORWARD_CURSOR;
       }
   ```
   
   I will follow this, ensure that operations do not block during large data volumes.
   


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