problem with OR'ed AND queriess

Using PQexec from libpq in postgresql 6.5.3, I submit a query of the
following form, which has 13 OR'ed AND expressions:

DECLARE my_cursor CURSOR FOR SELECT col1 FROM testCNF where
( ( col1=0 and col2=1 ) OR ( col1=1 and col2=2 ) OR
( col1=2 and col2=3 ) OR ( col1=3 and col2=4 ) OR
( col1=4 and col2=5 ) OR ( col1=5 and col2=6 ) OR
( col1=6 and col2=7 ) OR ( col1=7 and col2=8 ) OR
( col1=8 and col2=9 ) OR ( col1=9 and col2=10 ) OR
( col1=10 and col2=11 ) OR ( col1=11 and col2=12 ) OR
( col1=12 and col2=13 ) )

After 265 seconds, my test client gets back a NULL response from PQexec.
During the 265 seconds, the backend server machine (Sparc Ultra 2) slows
to a crawl. In the postmaster log, I see the following:

FATAL 1: Memory exhausted in AllocSetAlloc()

A similar query with 12 OR'ed AND expresions is successful, but only after
123 seconds. Queries with fewer OR'ed AND expresions get faster; 6 OR'ed
ANDS takes around one second. With other query types, I encounter no such
limitation; AND'ed ORs, all ANDs and all ORs can be as large a query as
the internal buffer can support (around 16k), with no problem.

I have traced the backend server in a debugger; a stack trace is attached
below. What I see in examining the code is a recursive normalization of
the query; postgres is running out of memory trying to convert the OR'ed
ANDs query to conjunctive normal form (CNF).

So, some questions for all you postgres gurus:

1. Has anyone else encountered this problem?

2. Has anyone patched the query optimizer to get around this problem, and
if so, where can I find the patch?

3. If I am truly the first to encounter this (which I doubt), how would I
go about altering the query optimizer to not fail on this valid query?

Thanks,

//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\//\\
Michael McCarthy TCSI Corporation
michael(at)tcsi(dot)com 1080 Marina Village Parkway
(510) 749-8739 Alameda, CA 94501

(/opt/packages/SUNWspro/bin/dbx) where
[1] AllocSetReset(0x56d488, 0x40aaf0, 0x1, 0x9c, 0x0, 0x0), at 0x285f80
[2] EndPortalAllocMode(0x502a70, 0x6fd0495c, 0x0, 0x0, 0x0, 0x0), at 0x28a398
[3] PortalResetHeapMemory(0x502a40, 0x0, 0x0, 0x0, 0x0, 0x0), at 0x289fcc
[4] AtAbort_Memory(0x0, 0x0, 0x0, 0x0, 0x0, 0x0), at 0xb68bc
[5] AbortTransaction(0x0, 0x0, 0x0, 0x0, 0x0, 0x0), at 0xb6d8c
[6] AbortOutOfAnyTransaction(0x0, 0x6feaa484, 0x4d88c8, 0x5015a7, 0x6fea2ca4, 0x0), at 0xb740c
[7] remove_all_temp_relations(0x0, 0x0, 0x0, 0x0, 0x6fea2ca4, 0x0), at 0x27c5dc
[8] shmem_exit(0x0, 0x409c98, 0x0, 0x0, 0x0, 0x0), at 0x1df424
[9] proc_exit(0x0, 0x6feaa484, 0x2e, 0x7efefeff, 0x6fea2ca4, 0x27d294), at 0x1df214
[10] elog(0x1, 0x411a00, 0x0, 0x0, 0x0, 0x0), at 0x27d58c
[11] AllocSetAlloc(0x56d488, 0xc, 0x0, 0x0, 0x0, 0x0), at 0x2866cc
[12] PortalHeapMemoryAlloc(0x502a70, 0xc, 0x0, 0x0, 0x0, 0x0), at 0x287f34
[13] MemoryContextAlloc(0x502a70, 0xc, 0x0, 0x0, 0x0, 0x0), at 0x286fdc
[14] newNode(0xc, 0x1f5, 0x0, 0x0, 0x0, 0x0), at 0x168928
[15] lcons(0x1f66e5c8, 0x0, 0x0, 0x0, 0x0, 0x0), at 0x168b6c
[16] copyObject(0x1f662a90, 0x66, 0x0, 0x0, 0x0, 0x0), at 0x16ecf4
[17] _copyExpr(0x1f662998, 0x1f5, 0x0, 0x0, 0x0, 0x0), at 0x16b3e8
[18] copyObject(0x1f662998, 0x0, 0x0, 0x0, 0x0, 0x0), at 0x16e7c4
[19] copyObject(0x1f662980, 0x66, 0x0, 0x0, 0x0, 0x0), at 0x16ecdc
[20] _copyExpr(0x1f661e50, 0x14, 0x0, 0x0, 0x0, 0x0), at 0x16b3e8
[21] copyObject(0x1f661e50, 0x14, 0x0, 0x0, 0x0, 0x0), at 0x16e7c4
[22] copyObject(0x1f6634b8, 0x66, 0x0, 0x0, 0x0, 0x0), at 0x16ec94
[23] _copyExpr(0x1f661e28, 0x1f5, 0x0, 0x0, 0x0, 0x0), at 0x16b3e8
[24] copyObject(0x1f661e28, 0x0, 0x0, 0x0, 0x0, 0x0), at 0x16e7c4
[25] copyObject(0x1f661e10, 0x66, 0x0, 0x0, 0x0, 0x0), at 0x16ecdc
[26] _copyExpr(0x1f660740, 0x14, 0x0, 0x0, 0x0, 0x0), at 0x16b3e8
[27] copyObject(0x1f660740, 0x14, 0x0, 0x0, 0x0, 0x0), at 0x16e7c4
[28] copyObject(0x1f6634e8, 0x66, 0x0, 0x0, 0x0, 0x0), at 0x16ec94
[29] _copyExpr(0x1f660718, 0x1f5, 0x0, 0x0, 0x0, 0x0), at 0x16b3e8
[30] copyObject(0x1f660718, 0x0, 0x0, 0x0, 0x0, 0x0), at 0x16e7c4
[31] copyObject(0x1f660700, 0x66, 0x0, 0x0, 0x0, 0x0), at 0x16ecdc
[32] _copyExpr(0x1f65d8f0, 0xc, 0x0, 0x0, 0x0, 0x0), at 0x16b3e8
[33] copyObject(0x1f65d8f0, 0xc, 0x0, 0x0, 0x0, 0x0), at 0x16e7c4
[34] copyObject(0x1f663518, 0xc, 0x0, 0x0, 0x0, 0x0), at 0x16ec94
[35] pull_ors(0x1f669210, 0x1f5, 0x0, 0x0, 0x0, 0x0), at 0x19d584
[36] pull_ors(0x1f669228, 0x1f669210, 0x0, 0x0, 0x0, 0x0), at 0x19d5f8
[37] distribute_args(0x69ace48, 0x1f663530, 0x0, 0x0, 0x0, 0x0), at 0x19dd64
[38] or_normalize(0x1f6691f8, 0x1f65d870, 0x0, 0x0, 0x0, 0x0), at 0x19dc34
[39] distribute_args(0x69ace48, 0x1f651e90, 0x0, 0x0, 0x0, 0x0), at 0x19dd74
[40] or_normalize(0x1f65d858, 0x1f6464d0, 0x0, 0x0, 0x0, 0x0), at 0x19dc34
[41] distribute_args(0x69ace48, 0x1f62f0f0, 0x0, 0x0, 0x0, 0x0), at 0x19dd74
[42] or_normalize(0x1f6464b8, 0x1f617d30, 0x0, 0x0, 0x0, 0x0), at 0x19dc34
[43] distribute_args(0x69ace48, 0x1f49fb58, 0x0, 0x0, 0x0, 0x0), at 0x19dd74
[44] or_normalize(0x1f4ce320, 0x1f471398, 0x0, 0x0, 0x0, 0x0), at 0x19dc34
[45] distribute_args(0x69ace48, 0x1f123fd8, 0x0, 0x0, 0x0, 0x0), at 0x19dd74
[46] or_normalize(0x1f180fa0, 0x1f0c7018, 0x0, 0x0, 0x0, 0x0), at 0x19dc34
[47] distribute_args(0x69ace48, 0x1e972820, 0x0, 0x0, 0x0, 0x0), at 0x19dd74
[48] or_normalize(0x1ea2c7e8, 0x1e8b8860, 0x0, 0x0, 0x0, 0x0), at 0x19dc34
[49] distribute_args(0x69ace48, 0x1e744880, 0x0, 0x0, 0x0, 0x0), at 0x19dd74
[50] or_normalize(0x1e8b8848, 0x1e5d08c0, 0x0, 0x0, 0x0, 0x0), at 0x19dc34
[51] distribute_args(0x69ace48, 0x1c2ae828, 0x0, 0x0, 0x0, 0x0), at 0x19dd74
[52] or_normalize(0x1c596810, 0x1bfc6868, 0x0, 0x0, 0x0, 0x0), at 0x19dc34
[53] distribute_args(0x69ace48, 0xf7d2280, 0x0, 0x0, 0x0, 0x0), at 0x19dd74
[54] or_normalize(0x1bfc6850, 0x1bfc6808, 0x0, 0x0, 0x0, 0x0), at 0x19dc34
[55] distribute_args(0x1333e468, 0x69ace00, 0x0, 0x0, 0x0, 0x0), at 0x19dd74
[56] or_normalize(0x1333e490, 0x6982cd0, 0x0, 0x0, 0x0, 0x0), at 0x19dc34
[57] or_normalize(0xbc660a0, 0x6982cd0, 0x0, 0x0, 0x0, 0x0), at 0x19dc64
[58] or_normalize(0x8ae9e58, 0x6982cd0, 0x0, 0x0, 0x0, 0x0), at 0x19dc64
[59] or_normalize(0x76afca8, 0x6982cd0, 0x0, 0x0, 0x0, 0x0), at 0x19dc64
[60] or_normalize(0x6e9ab00, 0x6982cd0, 0x0, 0x0, 0x0, 0x0), at 0x19dc64
[61] or_normalize(0x6b77150, 0x6982cd0, 0x0, 0x0, 0x0, 0x0), at 0x19dc64
[62] or_normalize(0x6a4a3d0, 0x6982cd0, 0x0, 0x0, 0x0, 0x0), at 0x19dc64
[63] or_normalize(0x69df050, 0x6982cd0, 0x0, 0x0, 0x0, 0x0), at 0x19dc64
[64] or_normalize(0x69bb5d0, 0x6982cd0, 0x0, 0x0, 0x0, 0x0), at 0x19dc64
[65] or_normalize(0x69b0ad0, 0x6982cd0, 0x69ada90, 0xefffa9e4, 0x3, 0x0), at 0x19dc64
[66] or_normalize(0x69adf90, 0x6982cd0, 0x0, 0xefff660b, 0x5734c8, 0x0), at 0x19dc64
[67] or_normalize(0x6982bb0, 0x69adae8, 0x0, 0x5a5ea8, 0x0, 0x0), at 0x19dc64
[68] normalize(0x6982a80, 0x0, 0x0, 0x0, 0x0, 0x5a5850), at 0x19cbdc
[69] cnfify(0x5a5f78, 0x1, 0x1, 0x0, 0x0, 0x5a5965), at 0x19c368
[70] query_planner(0x5a5a18, 0x1, 0x627458, 0x5a5f78, 0x54a55a, 0xf), at 0x194dfc
[71] union_planner(0x5a5a18, 0x0, 0xefff6098, 0xefff66d0, 0x70b, 0x70a), at 0x1958e0
[72] planner(0x5a5a18, 0x627410, 0x0, 0x5015ac, 0x51, 0xefffa9db), at 0x195380
[73] pg_parse_and_plan(0xefffaad3, 0x0, 0x0, 0xefffa9e4, 0x3, 0x0), at 0x1fc368
[74] pg_exec_query_dest(0xefffaad3, 0x3, 0x0, 0x5015ac, 0x6fea2ca4, 0x0), at 0x1fc628
[75] pg_exec_query(0xefffaad3, 0x40bdf8, 0x20202900, 0x7efefeff, 0x81010100, 0xff00), at 0x1fc568
[76] PostgresMain(0x4, 0xeffff0a4, 0x5, 0xeffff824, 0x0, 0xefffeba0), at 0x1febf8
=>[77] DoBackend(port = 0x4f5800), line 1628 in "postmaster.c"
[78] BackendStartup(port = 0x4f5800), line 1373 in "postmaster.c"
[79] ServerLoop(), line 823 in "postmaster.c"
[80] PostmasterMain(argc = 5, argv = 0xeffff824), line 616 in "postmaster.c"
[81] main(argc = 5, argv = 0xeffff824), line 93 in "main.c"