Hello,
I wonder, why do I get a Segmentation fault when I use mdb_put with MDB_RESERVE on a key that already exists ?
Simon Majou wrote:
Hello,
I wonder, why do I get a Segmentation fault when I use mdb_put with MDB_RESERVE on a key that already exists ?
Have no idea. Provide some more details and maybe we can guess.
LMDB version? stack trace from SEGV? What's the size of the existing record, what's the size of the new record? Show sample code that demonstrates the problem?
This is version 0.9.16
I used sample-bdb.txt for instance, with the DUP_SORT option, and the mdb_put with the MDB_RESERVED flags, and execute it 2 times. The first run (creation) is ok, the second (update) gets the seg fault.
I ran it in gdb and got the stack : #0 mdb_cursor_set (mc=mc@entry=0x7fffffffdb40, key=key@entry=0x7fffffffdda0,
data=data@entry=0x7fffffffd800, op=op@entry=MDB_SET, exactp=exactp@entry=0x7fffffffd7f0) at mdb.c:5867 #1 0x00007ffff7bd024c in mdb_cursor_put (mc=0x7fffffffdb40, key=0x7fffffffdda0, data=0x7fffffffd8f0, flags=32768) at mdb.c:6391 #2 0x00007ffff7bd095f in mdb_cursor_put (mc=0x7fffffffd9b0, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=<optimized out>) at mdb.c:6780 #3 0x00007ffff7bd29b2 in mdb_put (txn=<optimized out>, dbi=<optimized out>, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=65536) at mdb.c:8611 #4 0x0000000000400ccf in main (argc=1, argv=0x7fffffffded8) at sample-mdb.c:43
It seems the mp_lower value of the page is set to 0 instead of a value inside the page.
On 18 August 2015 at 13:58, Howard Chu hyc@symas.com wrote:
Simon Majou wrote:
Hello,
I wonder, why do I get a Segmentation fault when I use mdb_put with MDB_RESERVE on a key that already exists ?
Have no idea. Provide some more details and maybe we can guess.
LMDB version? stack trace from SEGV? What's the size of the existing record, what's the size of the new record? Show sample code that demonstrates the problem?
-- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/
Simon Majou wrote:
This is version 0.9.16
I used sample-bdb.txt for instance, with the DUP_SORT option, and the mdb_put with the MDB_RESERVED flags, and execute it 2 times. The first run (creation) is ok, the second (update) gets the seg fault.
DUPSORT and RESERVED are incompatible. RESERVED means you're not providing a data value, only a length. DUPSORT sorts *values* - since you didn't provide a valid value, it probably chased a pointer off into space.
I ran it in gdb and got the stack : #0 mdb_cursor_set (mc=mc@entry=0x7fffffffdb40, key=key@entry=0x7fffffffdda0, data=data@entry=0x7fffffffd800, op=op@entry=MDB_SET, exactp=exactp@entry=0x7fffffffd7f0) at mdb.c:5867 #1 0x00007ffff7bd024c in mdb_cursor_put (mc=0x7fffffffdb40, key=0x7fffffffdda0, data=0x7fffffffd8f0, flags=32768) at mdb.c:6391 #2 0x00007ffff7bd095f in mdb_cursor_put (mc=0x7fffffffd9b0, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=<optimized out>) at mdb.c:6780 #3 0x00007ffff7bd29b2 in mdb_put (txn=<optimized out>, dbi=<optimized out>, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=65536) at mdb.c:8611 #4 0x0000000000400ccf in main (argc=1, argv=0x7fffffffded8) at sample-mdb.c:43
It seems the mp_lower value of the page is set to 0 instead of a value inside the page.
On 18 August 2015 at 13:58, Howard Chu <hyc@symas.com mailto:hyc@symas.com> wrote:
Simon Majou wrote: Hello, I wonder, why do I get a Segmentation fault when I use mdb_put with MDB_RESERVE on a key that already exists ? Have no idea. Provide some more details and maybe we can guess. LMDB version? stack trace from SEGV? What's the size of the existing record, what's the size of the new record? Show sample code that demonstrates the problem? -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/--
Best regards,
Simon
Oh ok it makes sense now. Thank you for the heads up
On 18 August 2015 at 15:36, Howard Chu hyc@symas.com wrote:
Simon Majou wrote:
This is version 0.9.16
I used sample-bdb.txt for instance, with the DUP_SORT option, and the mdb_put with the MDB_RESERVED flags, and execute it 2 times. The first run (creation) is ok, the second (update) gets the seg fault.
DUPSORT and RESERVED are incompatible. RESERVED means you're not providing a data value, only a length. DUPSORT sorts *values* - since you didn't provide a valid value, it probably chased a pointer off into space.
I ran it in gdb and got the stack : #0 mdb_cursor_set (mc=mc@entry=0x7fffffffdb40, key=key@entry =0x7fffffffdda0, data=data@entry=0x7fffffffd800, op=op@entry=MDB_SET, exactp=exactp@entry=0x7fffffffd7f0) at mdb.c:5867 #1 0x00007ffff7bd024c in mdb_cursor_put (mc=0x7fffffffdb40, key=0x7fffffffdda0, data=0x7fffffffd8f0, flags=32768) at mdb.c:6391 #2 0x00007ffff7bd095f in mdb_cursor_put (mc=0x7fffffffd9b0, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=<optimized out>) at mdb.c:6780 #3 0x00007ffff7bd29b2 in mdb_put (txn=<optimized out>, dbi=<optimized out>, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=65536) at mdb.c:8611 #4 0x0000000000400ccf in main (argc=1, argv=0x7fffffffded8) at sample-mdb.c:43
It seems the mp_lower value of the page is set to 0 instead of a value inside the page.
On 18 August 2015 at 13:58, Howard Chu <hyc@symas.com mailto: hyc@symas.com> wrote:
Simon Majou wrote: Hello, I wonder, why do I get a Segmentation fault when I use mdb_putwith MDB_RESERVE on a key that already exists ?
Have no idea. Provide some more details and maybe we can guess. LMDB version? stack trace from SEGV? What's the size of the existing record, what's the size of the new record? Show sample code that demonstrates the problem? -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/--
Best regards,
Simon
-- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/
And in the case where I want to append data in a DUPSORT database, is there a way to write directly in the persisted page ? I tried with the flags MDB_RESERVE|MDB_APPEND but it fails.
On 18 August 2015 at 15:41, Simon Majou simon@majou.org wrote:
Oh ok it makes sense now. Thank you for the heads up
On 18 August 2015 at 15:36, Howard Chu hyc@symas.com wrote:
Simon Majou wrote:
This is version 0.9.16
I used sample-bdb.txt for instance, with the DUP_SORT option, and the mdb_put with the MDB_RESERVED flags, and execute it 2 times. The first run (creation) is ok, the second (update) gets the seg fault.
DUPSORT and RESERVED are incompatible. RESERVED means you're not providing a data value, only a length. DUPSORT sorts *values* - since you didn't provide a valid value, it probably chased a pointer off into space.
I ran it in gdb and got the stack : #0 mdb_cursor_set (mc=mc@entry=0x7fffffffdb40, key=key@entry =0x7fffffffdda0, data=data@entry=0x7fffffffd800, op=op@entry=MDB_SET, exactp=exactp@entry=0x7fffffffd7f0) at mdb.c:5867 #1 0x00007ffff7bd024c in mdb_cursor_put (mc=0x7fffffffdb40, key=0x7fffffffdda0, data=0x7fffffffd8f0, flags=32768) at mdb.c:6391 #2 0x00007ffff7bd095f in mdb_cursor_put (mc=0x7fffffffd9b0, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=<optimized out>) at mdb.c:6780 #3 0x00007ffff7bd29b2 in mdb_put (txn=<optimized out>, dbi=<optimized out>, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=65536) at mdb.c:8611 #4 0x0000000000400ccf in main (argc=1, argv=0x7fffffffded8) at sample-mdb.c:43
It seems the mp_lower value of the page is set to 0 instead of a value inside the page.
On 18 August 2015 at 13:58, Howard Chu <hyc@symas.com mailto: hyc@symas.com> wrote:
Simon Majou wrote: Hello, I wonder, why do I get a Segmentation fault when I use mdb_putwith MDB_RESERVE on a key that already exists ?
Have no idea. Provide some more details and maybe we can guess. LMDB version? stack trace from SEGV? What's the size of the existing record, what's the size of the new record? Show sample code that demonstrates the problem? -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/--
Best regards,
Simon
-- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/
--
Best regards,
Simon
Correction, with the flags MDB_RESERVE|MDB_APPENDDUP
Here is the stack from gdb :
Program received signal SIGSEGV, Segmentation fault. mdb_node_del (mc=mc@entry=0x7fffffffdb10, ksize=ksize@entry=0) at mdb.c:7183 7183 mp->mp_ptrs[j] = mp->mp_ptrs[i]; (gdb) bt #0 mdb_node_del (mc=mc@entry=0x7fffffffdb10, ksize=ksize@entry=0) at mdb.c:7183 #1 0x00007ffff7bd06e2 in mdb_cursor_put (mc=0x7fffffffdb10, key=0x7fffffffd8d0, data=0x7fffffffd8c0, flags=<optimized out>) at mdb.c:6698 #2 0x00007ffff7bd0f8e in mdb_cursor_put (mc=0x7fffffffd980, key=0x7fffffffdd70, data=0x7fffffffdda0, flags=<optimized out>) at mdb.c:6757 #3 0x00007ffff7bd29b2 in mdb_put (txn=<optimized out>, dbi=<optimized out>, key=0x7fffffffdd70, data=0x7fffffffdda0, flags=327680) at mdb.c:8611 #4 0x0000000000400dea in main (argc=1, argv=0x7fffffffded8) at test_lmdb_appenddup.c:59
On 21 August 2015 at 19:25, Simon Majou simon@majou.org wrote:
And in the case where I want to append data in a DUPSORT database, is there a way to write directly in the persisted page ? I tried with the flags MDB_RESERVE|MDB_APPEND but it fails.
On 18 August 2015 at 15:41, Simon Majou simon@majou.org wrote:
Oh ok it makes sense now. Thank you for the heads up
On 18 August 2015 at 15:36, Howard Chu hyc@symas.com wrote:
Simon Majou wrote:
This is version 0.9.16
I used sample-bdb.txt for instance, with the DUP_SORT option, and the mdb_put with the MDB_RESERVED flags, and execute it 2 times. The first run (creation) is ok, the second (update) gets the seg fault.
DUPSORT and RESERVED are incompatible. RESERVED means you're not providing a data value, only a length. DUPSORT sorts *values* - since you didn't provide a valid value, it probably chased a pointer off into space.
I ran it in gdb and got the stack : #0 mdb_cursor_set (mc=mc@entry=0x7fffffffdb40, key=key@entry =0x7fffffffdda0, data=data@entry=0x7fffffffd800, op=op@entry=MDB_SET, exactp=exactp@entry=0x7fffffffd7f0) at mdb.c:5867 #1 0x00007ffff7bd024c in mdb_cursor_put (mc=0x7fffffffdb40, key=0x7fffffffdda0, data=0x7fffffffd8f0, flags=32768) at mdb.c:6391 #2 0x00007ffff7bd095f in mdb_cursor_put (mc=0x7fffffffd9b0, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=<optimized out>) at mdb.c:6780 #3 0x00007ffff7bd29b2 in mdb_put (txn=<optimized out>, dbi=<optimized out>, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=65536) at mdb.c:8611 #4 0x0000000000400ccf in main (argc=1, argv=0x7fffffffded8) at sample-mdb.c:43
It seems the mp_lower value of the page is set to 0 instead of a value inside the page.
On 18 August 2015 at 13:58, Howard Chu <hyc@symas.com mailto: hyc@symas.com> wrote:
Simon Majou wrote: Hello, I wonder, why do I get a Segmentation fault when I use mdb_putwith MDB_RESERVE on a key that already exists ?
Have no idea. Provide some more details and maybe we can guess. LMDB version? stack trace from SEGV? What's the size of the existing record, what's the size of the new record? Show sample code that demonstrates the problem? -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/--
Best regards,
Simon
-- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/
--
Best regards,
Simon
--
Best regards,
Simon
Simon Majou wrote:
Correction, with the flags MDB_RESERVE|MDB_APPENDDUP
What part of "DUPSORT and RESERVE are incompatible" do you not understand?
Here is the stack from gdb :
Program received signal SIGSEGV, Segmentation fault. mdb_node_del (mc=mc@entry=0x7fffffffdb10, ksize=ksize@entry=0) at mdb.c:7183 7183 mp->mp_ptrs[j] = mp->mp_ptrs[i]; (gdb) bt #0 mdb_node_del (mc=mc@entry=0x7fffffffdb10, ksize=ksize@entry=0) at mdb.c:7183 #1 0x00007ffff7bd06e2 in mdb_cursor_put (mc=0x7fffffffdb10, key=0x7fffffffd8d0, data=0x7fffffffd8c0, flags=<optimized out>) at mdb.c:6698 #2 0x00007ffff7bd0f8e in mdb_cursor_put (mc=0x7fffffffd980, key=0x7fffffffdd70, data=0x7fffffffdda0, flags=<optimized out>) at mdb.c:6757 #3 0x00007ffff7bd29b2 in mdb_put (txn=<optimized out>, dbi=<optimized out>, key=0x7fffffffdd70, data=0x7fffffffdda0, flags=327680) at mdb.c:8611 #4 0x0000000000400dea in main (argc=1, argv=0x7fffffffded8) at test_lmdb_appenddup.c:59
On 21 August 2015 at 19:25, Simon Majou <simon@majou.org mailto:simon@majou.org> wrote:
And in the case where I want to append data in a DUPSORT database, is there a way to write directly in the persisted page ? I tried with the flags MDB_RESERVE|MDB_APPEND but it fails. On 18 August 2015 at 15:41, Simon Majou <simon@majou.org <mailto:simon@majou.org>> wrote: Oh ok it makes sense now. Thank you for the heads up On 18 August 2015 at 15:36, Howard Chu <hyc@symas.com <mailto:hyc@symas.com>> wrote: Simon Majou wrote: This is version 0.9.16 I used sample-bdb.txt for instance, with the DUP_SORT option, and the mdb_put with the MDB_RESERVED flags, and execute it 2 times. The first run (creation) is ok, the second (update) gets the seg fault. DUPSORT and RESERVED are incompatible. RESERVED means you're not providing a data value, only a length. DUPSORT sorts *values* - since you didn't provide a valid value, it probably chased a pointer off into space. I ran it in gdb and got the stack : #0 mdb_cursor_set (mc=mc@entry=0x7fffffffdb40, key=key@entry=0x7fffffffdda0, data=data@entry=0x7fffffffd800, op=op@entry=MDB_SET, exactp=exactp@entry=0x7fffffffd7f0) at mdb.c:5867 #1 0x00007ffff7bd024c in mdb_cursor_put (mc=0x7fffffffdb40, key=0x7fffffffdda0, data=0x7fffffffd8f0, flags=32768) at mdb.c:6391 #2 0x00007ffff7bd095f in mdb_cursor_put (mc=0x7fffffffd9b0, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=<optimized out>) at mdb.c:6780 #3 0x00007ffff7bd29b2 in mdb_put (txn=<optimized out>, dbi=<optimized out>, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=65536) at mdb.c:8611 #4 0x0000000000400ccf in main (argc=1, argv=0x7fffffffded8) at sample-mdb.c:43 It seems the mp_lower value of the page is set to 0 instead of a value inside the page. On 18 August 2015 at 13:58, Howard Chu <hyc@symas.com <mailto:hyc@symas.com> <mailto:hyc@symas.com <mailto:hyc@symas.com>>> wrote: Simon Majou wrote: Hello, I wonder, why do I get a Segmentation fault when I use mdb_put with MDB_RESERVE on a key that already exists ? Have no idea. Provide some more details and maybe we can guess. LMDB version? stack trace from SEGV? What's the size of the existing record, what's the size of the new record? Show sample code that demonstrates the problem? -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/ -- Best regards, Simon -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/ -- Best regards, Simon -- Best regards, Simon--
Best regards,
Simon
In your previous mail you said they were incompatible, but you provided a logical reason why (you can't sort the data). Now I found a case where the reason doesn't apply (you can append without doing the comparison). So I thought maybe there was something else I missed. But ok I understand this is not supported.
On 21 August 2015 at 21:21, Howard Chu hyc@symas.com wrote:
Simon Majou wrote:
Correction, with the flags MDB_RESERVE|MDB_APPENDDUP
What part of "DUPSORT and RESERVE are incompatible" do you not understand?
Here is the stack from gdb :
Program received signal SIGSEGV, Segmentation fault. mdb_node_del (mc=mc@entry=0x7fffffffdb10, ksize=ksize@entry=0) at mdb.c:7183 7183 mp->mp_ptrs[j] = mp->mp_ptrs[i]; (gdb) bt #0 mdb_node_del (mc=mc@entry=0x7fffffffdb10, ksize=ksize@entry=0) at mdb.c:7183 #1 0x00007ffff7bd06e2 in mdb_cursor_put (mc=0x7fffffffdb10, key=0x7fffffffd8d0, data=0x7fffffffd8c0, flags=<optimized out>) at mdb.c:6698 #2 0x00007ffff7bd0f8e in mdb_cursor_put (mc=0x7fffffffd980, key=0x7fffffffdd70, data=0x7fffffffdda0, flags=<optimized out>) at mdb.c:6757 #3 0x00007ffff7bd29b2 in mdb_put (txn=<optimized out>, dbi=<optimized out>, key=0x7fffffffdd70, data=0x7fffffffdda0, flags=327680) at mdb.c:8611 #4 0x0000000000400dea in main (argc=1, argv=0x7fffffffded8) at test_lmdb_appenddup.c:59
On 21 August 2015 at 19:25, Simon Majou <simon@majou.org mailto:simon@majou.org> wrote:
And in the case where I want to append data in a DUPSORT database, is there a way to write directly in the persisted page ? I tried with the flags MDB_RESERVE|MDB_APPEND but it fails. On 18 August 2015 at 15:41, Simon Majou <simon@majou.org <mailto:simon@majou.org>> wrote: Oh ok it makes sense now. Thank you for the heads up On 18 August 2015 at 15:36, Howard Chu <hyc@symas.com <mailto:hyc@symas.com>> wrote: Simon Majou wrote: This is version 0.9.16 I used sample-bdb.txt for instance, with the DUP_SORToption, and the mdb_put with the MDB_RESERVED flags, and execute it 2 times. The first run (creation) is ok, the second (update) gets the seg fault.
DUPSORT and RESERVED are incompatible. RESERVED means you'renot providing a data value, only a length. DUPSORT sorts *values*
since you didn't provide a valid value, it probably chased a pointer off into space. I ran it in gdb and got the stack : #0 mdb_cursor_set (mc=mc@entry=0x7fffffffdb40, key=key@entry=0x7fffffffdda0, data=data@entry=0x7fffffffd800, op=op@entry=MDB_SET, exactp=exactp@entry=0x7fffffffd7f0) at mdb.c:5867 #1 0x00007ffff7bd024c in mdb_cursor_put (mc=0x7fffffffdb40, key=0x7fffffffdda0, data=0x7fffffffd8f0, flags=32768) at mdb.c:6391 #2 0x00007ffff7bd095f in mdb_cursor_put (mc=0x7fffffffd9b0, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=<optimized out>) at mdb.c:6780 #3 0x00007ffff7bd29b2 in mdb_put (txn=<optimized out>, dbi=<optimized out>, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=65536) at mdb.c:8611 #4 0x0000000000400ccf in main (argc=1, argv=0x7fffffffded8) at sample-mdb.c:43
It seems the mp_lower value of the page is set to 0instead of a value inside the page.
On 18 August 2015 at 13:58, Howard Chu <hyc@symas.com <mailto:hyc@symas.com> <mailto:hyc@symas.com <mailto:hyc@symas.com>>> wrote: Simon Majou wrote: Hello, I wonder, why do I get a Segmentation fault whenI use mdb_put with MDB_RESERVE on a key that already exists ?
Have no idea. Provide some more details and maybe wecan guess.
LMDB version? stack trace from SEGV? What's the sizeof the existing record, what's the size of the new record? Show sample code that demonstrates the problem?
-- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sunhttp://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/
-- Best regards, Simon -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/ -- Best regards, Simon -- Best regards, Simon--
Best regards,
Simon
-- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/
Simon Majou wrote:
In your previous mail you said they were incompatible, but you provided a logical reason why (you can't sort the data). Now I found a case where the reason doesn't apply (you can append without doing the comparison).
No, you can't.
http://symas.com/mdb/doc/group__mdb.html#ga4fa8573d9236d54687c61827ebf8cac0
"Loading unsorted keys with this flag will cause a MDB_KEYEXIST error."
The key is always checked, because not checking it would allow the DB to become corrupted. Again, with RESERVE, you're not providing anything that can be checked.
So I thought maybe there was something else I missed. But ok I understand this is not supported.
For exactly the same reason as I already told you.
On 21 August 2015 at 21:21, Howard Chu <hyc@symas.com mailto:hyc@symas.com> wrote:
Simon Majou wrote: Correction, with the flags MDB_RESERVE|MDB_APPENDDUP What part of "DUPSORT and RESERVE are incompatible" do you not understand? Here is the stack from gdb : Program received signal SIGSEGV, Segmentation fault. mdb_node_del (mc=mc@entry=0x7fffffffdb10, ksize=ksize@entry=0) at mdb.c:7183 7183 mp->mp_ptrs[j] = mp->mp_ptrs[i]; (gdb) bt #0 mdb_node_del (mc=mc@entry=0x7fffffffdb10, ksize=ksize@entry=0) at mdb.c:7183 #1 0x00007ffff7bd06e2 in mdb_cursor_put (mc=0x7fffffffdb10, key=0x7fffffffd8d0, data=0x7fffffffd8c0, flags=<optimized out>) at mdb.c:6698 #2 0x00007ffff7bd0f8e in mdb_cursor_put (mc=0x7fffffffd980, key=0x7fffffffdd70, data=0x7fffffffdda0, flags=<optimized out>) at mdb.c:6757 #3 0x00007ffff7bd29b2 in mdb_put (txn=<optimized out>, dbi=<optimized out>, key=0x7fffffffdd70, data=0x7fffffffdda0, flags=327680) at mdb.c:8611 #4 0x0000000000400dea in main (argc=1, argv=0x7fffffffded8) at test_lmdb_appenddup.c:59 On 21 August 2015 at 19:25, Simon Majou <simon@majou.org <mailto:simon@majou.org> <mailto:simon@majou.org <mailto:simon@majou.org>>> wrote: And in the case where I want to append data in a DUPSORT database, is there a way to write directly in the persisted page ? I tried with the flags MDB_RESERVE|MDB_APPEND but it fails. On 18 August 2015 at 15:41, Simon Majou <simon@majou.org <mailto:simon@majou.org> <mailto:simon@majou.org <mailto:simon@majou.org>>> wrote: Oh ok it makes sense now. Thank you for the heads up On 18 August 2015 at 15:36, Howard Chu <hyc@symas.com <mailto:hyc@symas.com> <mailto:hyc@symas.com <mailto:hyc@symas.com>>> wrote: Simon Majou wrote: This is version 0.9.16 I used sample-bdb.txt for instance, with the DUP_SORT option, and the mdb_put with the MDB_RESERVED flags, and execute it 2 times. The first run (creation) is ok, the second (update) gets the seg fault. DUPSORT and RESERVED are incompatible. RESERVED means you're not providing a data value, only a length. DUPSORT sorts *values* - since you didn't provide a valid value, it probably chased a pointer off into space. I ran it in gdb and got the stack : #0 mdb_cursor_set (mc=mc@entry=0x7fffffffdb40, key=key@entry=0x7fffffffdda0, data=data@entry=0x7fffffffd800, op=op@entry=MDB_SET, exactp=exactp@entry=0x7fffffffd7f0) at mdb.c:5867 #1 0x00007ffff7bd024c in mdb_cursor_put (mc=0x7fffffffdb40, key=0x7fffffffdda0, data=0x7fffffffd8f0, flags=32768) at mdb.c:6391 #2 0x00007ffff7bd095f in mdb_cursor_put (mc=0x7fffffffd9b0, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=<optimized out>) at mdb.c:6780 #3 0x00007ffff7bd29b2 in mdb_put (txn=<optimized out>, dbi=<optimized out>, key=0x7fffffffdd90, data=0x7fffffffdda0, flags=65536) at mdb.c:8611 #4 0x0000000000400ccf in main (argc=1, argv=0x7fffffffded8) at sample-mdb.c:43 It seems the mp_lower value of the page is set to 0 instead of a value inside the page. On 18 August 2015 at 13:58, Howard Chu <hyc@symas.com <mailto:hyc@symas.com> <mailto:hyc@symas.com <mailto:hyc@symas.com>> <mailto:hyc@symas.com <mailto:hyc@symas.com> <mailto:hyc@symas.com <mailto:hyc@symas.com>>>> wrote: Simon Majou wrote: Hello, I wonder, why do I get a Segmentation fault when I use mdb_put with MDB_RESERVE on a key that already exists ? Have no idea. Provide some more details and maybe we can guess. LMDB version? stack trace from SEGV? What's the size of the existing record, what's the size of the new record? Show sample code that demonstrates the problem? -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/
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Simon Majou