#At file:///Users/shulga/projects/mysql/mysql-5.5-merge/ based on revid:mikael@dator8-20100916080410-9pd2sv3zreil1wy6
3206 Dmitry Shulga 2010-09-16 [merge]
Auto-merge from mysql-5.1-bugteam for bug#42503.
=== modified file 'sql/net_serv.cc'
--- a/sql/net_serv.cc 2010-08-05 12:53:09 +0000
+++ b/sql/net_serv.cc 2010-09-16 10:38:13 +0000
@@ -164,7 +164,17 @@ my_bool net_realloc(NET *net, size_t len
DBUG_PRINT("enter",("length: %lu", (ulong) length));
- if (length >= net->max_packet_size)
+ When compression is off, net->where_b is always 0.
+ With compression turned on, net->where_b may indicate
+ that we still have a piece of the previous logical
+ packet in the buffer, unprocessed. Take it into account
+ when checking that max_allowed_packet is not exceeded.
+ This ensures that the client treats max_allowed_packet
+ limit identically, regardless of compression being on
+ or off.
+ if (length >= (net->max_packet_size + net->where_b))
DBUG_PRINT("error", ("Packet too large. Max size: %lu",
=== modified file 'sql/sql_cache.cc'
--- a/sql/sql_cache.cc 2010-07-24 01:36:21 +0000
+++ b/sql/sql_cache.cc 2010-09-16 10:38:13 +0000
@@ -1346,6 +1346,55 @@ end:
+ Send a single memory block from the query cache.
+ Respects the client/server protocol limits for the
+ size of the network packet, and splits a large block
+ in pieces to ensure that individual piece doesn't exceed
+ the maximal allowed size of the network packet (16M).
+ @param[in] net NET handler
+ @param[in] packet packet to send
+ @param[in] len packet length
+ @return Operation status
+ @retval FALSE On success
+ @retval TRUE On error
+send_data_in_chunks(NET *net, const uchar *packet, ulong len)
+ On the client we may require more memory than max_allowed_packet
+ to keep, both, the truncated last logical packet, and the
+ compressed next packet. This never (or in practice never)
+ happens without compression, since without compression it's very
+ unlikely that a) a truncated logical packet would remain on the
+ client when it's time to read the next packet b) a subsequent
+ logical packet that is being read would be so large that
+ size-of-new-packet + size-of-old-packet-tail >
+ max_allowed_packet. To remedy this issue, we send data in 1MB
+ sized packets, that's below the current client default of 16MB
+ for max_allowed_packet, but large enough to ensure there is no
+ unnecessary overhead from too many syscalls per result set.
+ static const ulong MAX_CHUNK_LENGTH= 1024*1024;
+ while (len > MAX_CHUNK_LENGTH)
+ if (net_real_write(net, packet, MAX_CHUNK_LENGTH))
+ return TRUE;
+ packet+= MAX_CHUNK_LENGTH;
+ len-= MAX_CHUNK_LENGTH;
+ if (len && net_real_write(net, packet, len))
+ return TRUE;
+ return FALSE;
Check if the query is in the cache. If it was cached, send it
to the user.
@@ -1655,11 +1704,11 @@ def_week_frmt: %lu, in_trans: %d, autoco
Query_cache_result *result = result_block->result();
- if (net_real_write(&thd->net, result->data(),
- result_block->used -
- result_block->headers_len() -
- break; // Client aborted
+ if (send_data_in_chunks(&thd->net, result->data(),
+ result_block->used -
+ result_block->headers_len() -
+ break; // Client aborted
result_block = result_block->next;
thd->net.pkt_nr= query->last_pkt_nr; // Keep packet number updated
} while (result_block != first_result_block);
Attachment: [text/bzr-bundle] email@example.com
|• bzr commit into mysql-5.5-merge branch (Dmitry.Shulga:3206) Bug#42503||Dmitry Shulga||16 Sep|