Commit5776847

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Correct assertion and comments about XLogRecordMaxSize.

The largest allocation, of xl_tot_len+8192, is in allocate_recordbuf().Discussion:https://postgr.es/m/20230812211327.GB2326466@rfd.leadboat.com

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Lines changed: 5 additions & 4 deletions

Original file line number	Diff line number	Diff line change
`@@ -897,8 +897,7 @@ XLogRecordAssemble(RmgrId rmid, uint8 info,`
`897`	`897`	`*`
`898`	`898`	`* XLogReader machinery is only able to handle records up to a certain`
`899`	`899`	`* size (ignoring machine resource limitations), so make sure that we will`
`900`		`- * not emit records larger than the sizes advertised to be supported. This`
`901`		`- * cap is based on DecodeXLogRecordRequiredSpace().`
	`900`	`+ * not emit records larger than the sizes advertised to be supported.`
`902`	`901`	`*/`
`903`	`902`	`if (total_len>XLogRecordMaxSize)`
`904`	`903`	`ereport(ERROR,`
`@@ -1339,10 +1338,12 @@ InitXLogInsert(void)`
`1339`	`1338`
`1340`	`1339`	`/*`
`1341`	`1340`	`* Check that any records assembled can be decoded. This is capped based`
`1342`		`- * on what XLogReader would require at its maximum bound. This code path`
	`1341`	`+ * on what XLogReader would require at its maximum bound. The XLOG_BLCKSZ`
	`1342`	`+ * addend covers the larger allocate_recordbuf() demand. This code path`
`1343`	`1343`	`* is called once per backend, more than enough for this check.`
`1344`	`1344`	`*/`
`1345`		`-size_tmax_required=DecodeXLogRecordRequiredSpace(XLogRecordMaxSize);`
	`1345`	`+size_tmax_required=`
	`1346`	`+DecodeXLogRecordRequiredSpace(XLogRecordMaxSize+XLOG_BLCKSZ);`
`1346`	`1347`
`1347`	`1348`	`Assert(AllocSizeIsValid(max_required));`
`1348`	`1349`	`#endif`

Lines changed: 2 additions & 2 deletions

Original file line number	Diff line number	Diff line change
`@@ -68,8 +68,8 @@ typedef struct XLogRecord`
`68`	`68`	`* in length if we ignore any allocation overhead of the XLogReader.`
`69`	`69`	`*`
`70`	`70`	`* To accommodate some overhead, this value allows for 4M of allocation`
`71`		`- * overhead, that should be plenty enough for what`
`72`		`- *DecodeXLogRecordRequiredSpace() expects as extra.`
	`71`	`+ * overhead, that should be plenty enough for what the XLogReader`
	`72`	`+ *infrastructure expects as extra.`
`73`	`73`	`*/`
`74`	`74`	`#defineXLogRecordMaxSize(1020 * 1024 * 1024)`
`75`	`75`

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