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Commit69949ea

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Adjust pg_dump's priority ordering for casts.
When a stored expression depends on a user-defined cast, the backendrecords the dependency as being on the cast's implementation function--- or indeed, if there's no cast function involved but justRelabelType or CoerceViaIO, no dependency is recorded at all. Thisis problematic for pg_dump, which is at risk of dumping things in thewrong order leading to restore failures. Given the lack of previousreports, the risk isn't that high, but it can be demonstrated if thecast is used in some view whose rowtype is then used as an input orresult type for some other function. (That results in the viewgetting hoisted into the functions portion of the dump, ahead ofthe cast.)A logically bulletproof fix for this would require including thecast's OID in the parsed form of the expression, whence it could beextracted by dependency.c, and then the stored dependency would forcepg_dump to do the right thing. Such a change would be fairly invasive,and certainly not back-patchable. Moreover, since we'd prefer thatan expression using cast syntax be equal() to one doing the samething by explicit function call, the cast OID field would have tohave special ignored-by-comparisons semantics, making things messy.So, let's instead fix this by a very simple hack in pg_dump: changethe object-type priority order so that casts are initially sortedbefore functions, immediately after types. This fixes the problemin a fairly direct way for casts that have no implementation function.For those that do, the implementation function will be hoisted to justbefore the cast by the dependency sorting step, so that we still havea valid dump order. (I'm not sure that this provides a full guaranteeof no problems; but since it's been like this for many years withoutany previous reports, this is probably enough to fix it in practice.)Per report from Дмитрий Иванов.Back-patch to all supported branches.Discussion:https://postgr.es/m/CAPL5KHoGa3uvyKp6z6m48LwCnTsK+LRQ_mcA4uKGfqAVSEjV_A@mail.gmail.com
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‎src/bin/pg_dump/pg_dump_sort.c

Lines changed: 16 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -35,6 +35,15 @@
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* restore state). If you think to change this, see also the RestorePass
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* mechanism in pg_backup_archiver.c.
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*
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* On the other hand, casts are intentionally sorted earlier than you might
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* expect; logically they should come after functions, since they usually
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* depend on those. This works around the backend's habit of recording
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* views that use casts as dependent on the cast's underlying function.
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* We initially sort casts first, and then any functions used by casts
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* will be hoisted above the casts, and in turn views that those functions
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* depend on will be hoisted above the functions. But views not used that
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* way won't be hoisted.
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*
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* NOTE: object-type priorities must match the section assignments made in
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* pg_dump.c; that is, PRE_DATA objects must sort before DO_PRE_DATA_BOUNDARY,
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* POST_DATA objects must sort after DO_POST_DATA_BOUNDARY, and DATA objects
@@ -46,12 +55,12 @@ static const int dbObjectTypePriority[] =
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4,/* DO_EXTENSION */
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5,/* DO_TYPE */
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5,/* DO_SHELL_TYPE */
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6,/* DO_FUNC */
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7,/* DO_AGG */
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8,/* DO_OPERATOR */
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8,/* DO_ACCESS_METHOD */
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9,/* DO_OPCLASS */
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9,/* DO_OPFAMILY */
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7,/* DO_FUNC */
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8,/* DO_AGG */
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9,/* DO_OPERATOR */
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9,/* DO_ACCESS_METHOD */
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10,/* DO_OPCLASS */
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10,/* DO_OPFAMILY */
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3,/* DO_COLLATION */
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11,/* DO_CONVERSION */
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18,/* DO_TABLE */
@@ -64,7 +73,7 @@ static const int dbObjectTypePriority[] =
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27,/* DO_CONSTRAINT */
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33,/* DO_FK_CONSTRAINT */
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2,/* DO_PROCLANG */
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10,/* DO_CAST */
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6,/* DO_CAST */
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23,/* DO_TABLE_DATA */
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24,/* DO_SEQUENCE_SET */
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19,/* DO_DUMMY_TYPE */

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