table .frm file
Problem:
========
Myisampack --join did not create the destination table .frm file.
The user had to copy one of the source table .frm file as destination .frm
file for mysql server to recognize. This is just 'user-friendliness' issue.
How it was solved
=================
After successful join and compression we copy the frm file from the first
source table.
Functionality added
===================
myisampack --join=/path/t3 /path/t1 /path/t2 creates
/path/t3.frm (which is bascially copied from first table's frm /path/t1)
Tests
=====
Modified myisampack.test to test two scenario's
1. Positive myisampack --join test
In this case after the join operation is done,we test if the destination
table is accessible from the server
2. Positive myisampack --join test with an existing .frm file.
We test the above case with an existing .frm file for the destination
table. It should return success even in this case.
3. Positive myisampack --join test with no .frm file for source tables
We test the join operation with no .frm files for source tables. It should
complete the join operation without any warnings and error messages
4. Negative myisampack --join test
We test myisampack --join with existing .MYI,.MDI,.frm files for the
destination table. It should fail with exit status 2 in this case.
The test started failing following the push for BUG#41541.
Some of the algorithms access bytes beyond the input data
and this can affect up to one byte less than "word size"
which is BITS_SAVED / 8.
Fixed by adding (BITS_SAVED / 8) -1 bytes to buffer size
(i.e. Memory Segment #2) to avoid accessing un-allocated data.
After the table is compressed by the myisampack utility,
opening the table by the server produces valgrind warnings.
This happens because when we try to read a record into the buffer
we alway assume that the remaining buffer to read is always equal
to word size(4 or 8 or 2 bytes) we read. Sometimes we have
remaining buffer size less than word size and trying to read the
entire word size will end up in valgrind errors.
Fixed by reading byte by byte when we detect the remaining buffer
size is less than the word size.
With certain data sets (when compressed record length gets bigger than
uncompressed) myisamchk --unpack may corrupt data file.
Fixed that record length was wrongly restored from compressed table.
