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Fix mysql return bug #4450

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Merged
morningman merged 3 commits into from
Aug 27, 2020
Merged

Fix mysql return bug #4450

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cde69da
fix mysql return bug
Aug 25, 2020
e1a7d96
fix bug
Aug 25, 2020
9c326d5
add comment
Aug 26, 2020
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16 changes: 10 additions & 6 deletions fe/fe-core/src/main/java/org/apache/doris/qe/StmtExecutor.java
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Original file line number Diff line number Diff line change
Expand Up @@ -608,9 +608,6 @@ private void handleQueryStmt() throws Exception {

coord.exec();

// if python's MysqlDb get error after sendfields, it can't catch the exception
// so We need to send fields after first batch arrived

// send result
// 1. If this is a query with OUTFILE clause, eg: select * from tbl1 into outfile xxx,
// We will not send real query result to client. Instead, we only send OK to client with
Expand All @@ -622,13 +619,17 @@ private void handleQueryStmt() throws Exception {
RowBatch batch;
MysqlChannel channel = context.getMysqlChannel();
boolean isOutfileQuery = queryStmt.hasOutFileClause();
if (!isOutfileQuery) {
sendFields(queryStmt.getColLabels(), queryStmt.getResultExprs());
}
boolean isSendFields = false;
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@morningman morningman Aug 25, 2020

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So the reason is that the fields has been sent but no data is sent following?

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@gengjun-git gengjun-git Aug 26, 2020

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Yes, fields has been sent, but query may fail because of timeout. In this case, client will get a fields packet, and error packet, but some language mysql driver cannot recognize the error, and returns a success and no rows result.

while (true) {
batch = coord.getNext();
// for outfile query, there will be only one empty batch send back with eos flag
if (batch.getBatch() != null && !isOutfileQuery) {
// For some language driver, getting error packet after fields packet will be recognized as a success result
// so We need to send fields after first batch arrived
if (!isSendFields) {
sendFields(queryStmt.getColLabels(), queryStmt.getResultExprs());
isSendFields = true;
}
for (ByteBuffer row : batch.getBatch().getRows()) {
channel.sendOnePacket(row);
}
Expand All @@ -638,6 +639,9 @@ private void handleQueryStmt() throws Exception {
break;
}
}
if (!isSendFields && !isOutfileQuery) {
sendFields(queryStmt.getColLabels(), queryStmt.getResultExprs());
}

statisticsForAuditLog = batch.getQueryStatistics();
if (!isOutfileQuery) {
Expand Down