(gdb) bt
#0  0x00007fa235a73fe0 in read () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00000000006249fd in read (__nbytes=8192, __buf=0x7fa21f8d7ee0, 
    __fd=<optimized out>) at /usr/include/x86_64-linux-gnu/bits/unistd.h:45
#2  FileRead (file=<optimized out>, buffer=0x7fa21f8d7ee0 "RI", amount=8192)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/storage/file/fd.c:1191
#3  0x000000000063d856 in mdread (reln=<optimized out>, 
    forknum=<optimized out>, blocknum=253211, buffer=0x7fa21f8d7ee0 "RI")
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/storage/smgr/md.c:646
#4  0x0000000000620556 in ReadBuffer_common (smgr=<optimized out>, 
    relpersistence=112 'p', forkNum=MAIN_FORKNUM, blockNum=253211, 
    mode=RBM_NORMAL, strategy=<optimized out>, hit=0x7fffa31cb7df "")
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/storage/buffer/bufmgr.c:440
#5  0x0000000000621014 in ReadBufferExtended (reln=0x18678a0, 
    forkNum=MAIN_FORKNUM, blockNum=253211, mode=RBM_NORMAL, 
    strategy=<optimized out>)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/storage/buffer/bufmgr.c:246
#6  0x000000000046ff81 in heapgetpage (scan=0x2202340, page=253211)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/access/heap/heapam.c:230
#7  0x000000000047049a in heapgettup_pagemode (scan=0x2202340, 
    dir=<optimized out>, nkeys=0, key=0x0)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/access/heap/heapam.c:824
#8  0x0000000000471506 in heap_getnext (scan=0x2202340, 
    direction=<optimized out>)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/access/heap/heapam.c:1349
#9  0x000000000058a50b in SeqNext (node=<optimized out>)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/executor/nodeSeqscan.c:66
#10 0x0000000000579fa3 in ExecScanFetch (recheckMtd=0x58a4d0 <SeqRecheck>, 
    accessMtd=0x58a4e0 <SeqNext>, node=0x2201590)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/executor/execScan.c:82
#11 ExecScan (node=0x2201590, accessMtd=0x58a4e0 <SeqNext>, 
    recheckMtd=0x58a4d0 <SeqRecheck>)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/executor/execScan.c:167
#12 0x0000000000572a98 in ExecProcNode (node=0x2201590)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/executor/execProcnode.c:394
#13 0x000000000058587a in ExecLockRows (node=0x22013a0)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/executor/nodeLockRows.c:54
#14 0x0000000000572948 in ExecProcNode (node=0x22013a0)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/executor/execPro---Type <return> to continue, or q <return> to quit---
cnode.c:486
#15 0x000000000056fd62 in ExecutePlan (dest=0xafdea0, 
    direction=<optimized out>, numberTuples=1, sendTuples=1 '\001', 
    operation=CMD_SELECT, planstate=0x22013a0, estate=0x22011e0)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/executor/execMain.c:1442
#16 standard_ExecutorRun (queryDesc=0x21ff220, direction=<optimized out>, 
    count=1)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/executor/execMain.c:316
#17 0x000000000059341d in _SPI_pquery (tcount=<optimized out>, 
    fire_triggers=0 '\000', queryDesc=<optimized out>)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/executor/spi.c:2110
#18 _SPI_execute_plan (paramLI=0x21ff1d0, snapshot=<optimized out>, 
    crosscheck_snapshot=0x0, read_only=0 '\000', fire_triggers=0 '\000', 
    tcount=1, plan=<optimized out>)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/executor/spi.c:1922
#19 0x000000000059386e in SPI_execute_snapshot (plan=0x204a7d0, 
    Values=0x7fffa31cbcc0, Nulls=0x7fffa31cbed0 " ", snapshot=0x0, 
    crosscheck_snapshot=0x0, read_only=0 '\000', fire_triggers=0 '\000', 
    tcount=1)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/executor/spi.c:462
#20 0x00000000006c8d50 in ri_PerformCheck (qkey=0x7fffa31cbf90, 
    qplan=0x204a7d0, fk_rel=0x18678a0, pk_rel=0x1868c00, 
    old_tuple=0x7fffa31cca00, new_tuple=0x0, detectNewRows=1 '\001', 
    expect_OK=5, 
    constrname=0x7fffa31cc0d4 "api_apirecordconv_rec_submission_id_fkey")
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/utils/adt/ri_triggers.c:3427
#21 0x00000000006ca1f5 in RI_FKey_noaction_del (fcinfo=<optimized out>)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/utils/adt/ri_triggers.c:818
#22 0x0000000000555fda in ExecCallTriggerFunc (trigdata=0x7fffa31cc9d0, 
    tgindx=0, finfo=0x202c9b0, instr=0x0, per_tuple_context=<optimized out>)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/commands/trigger.c:1831
#23 0x000000000055668f in AfterTriggerExecute (per_tuple_context=0x2038280, 
    instr=0x0, finfo=0x202c9b0, rel=0x1868c00, event=0x21983a8, 
    trigdesc=<optimized out>)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/commands/trigger.c:3369
#24 afterTriggerInvokeEvents (events=0x1617ee0, firing_id=13, 
    estate=0x202c670, delete_ok=<optimized out>)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/commands/trigger.c:3548
#25 0x000000000055baf5 in AfterTriggerFireDeferred ()
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/commands/trigger---Type <return> to continue, or q <return> to quit---
.c:3795
#26 0x000000000048c8e5 in CommitTransaction ()
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/access/transam/xact.c:1785
#27 0x000000000048cf3d in CommitTransactionCommand ()
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/access/transam/xact.c:2563
#28 0x000000000064017b in finish_xact_command ()
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/tcop/postgres.c:2452
#29 finish_xact_command ()
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/tcop/postgres.c:2441
#30 0x00000000006437dd in exec_simple_query (query_string=0x16e9e60 "COMMIT;")
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/tcop/postgres.c:1051
#31 PostgresMain (argc=<optimized out>, argv=<optimized out>, 
    dbname=0x1613cc0 "siphon", username=<optimized out>)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/tcop/postgres.c:3976
#32 0x0000000000604443 in BackendRun (port=0x16570a0)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/postmaster/postmaster.c:3612
#33 BackendStartup (port=0x16570a0)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/postmaster/postmaster.c:3302
#34 ServerLoop ()
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/postmaster/postmaster.c:1466
#35 0x0000000000604eb1 in PostmasterMain (argc=<optimized out>, 
    argv=<optimized out>)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/postmaster/postmaster.c:1127
#36 0x000000000045a720 in main (argc=5, argv=0x1613180)
    at /build/buildd/postgresql-9.1-9.1.11/build/../src/backend/main/main.c:199