Improved comment on the pager.c PERSIST rollback journal delete logic

inside of hasHotJournal().  No changes to code.

FossilOrigin-Name: e5b17a9d07a35c9b44ff977ba81b93d745d26a11

1 files changed, 8 insertions, 6 deletions

diff --git a/src/pager.c b/src/pager.c
index e2486caa0..c6485a4d4 100644
--- a/src/pager.c
+++ b/src/pager.c
@@ -4889,14 +4889,16 @@ static int hasHotJournal(Pager *pPager, int *pExists){
     if( rc==SQLITE_OK && !locked ){
       Pgno nPage;                 /* Number of pages in database file */
 
-      /* Check the size of the database file. If it consists of 0 pages
-      ** and the journal is not being persisted, then delete the journal
-      ** file.  See the header comment above for the reasoning here.
-      ** Delete the obsolete journal file under a RESERVED lock to avoid
-      ** race conditions and to avoid violating [H33020].
-      */
       rc = pagerPagecount(pPager, &nPage);
       if( rc==SQLITE_OK ){
+        /* If the database is zero pages in size, that means that either (1) the
+        ** journal is a remnant from a prior database with the same name where
+        ** the database file but not the journal was deleted, or (2) the initial
+        ** transaction that populates a new database is being rolled back.
+        ** In either case, the journal file can be deleted.  However, take care
+        ** not to delete the journal file if it is already open due to
+        ** journal_mode=PERSIST.
+        */
         if( nPage==0 && !jrnlOpen ){
           sqlite3BeginBenignMalloc();
           if( pagerLockDb(pPager, RESERVED_LOCK)==SQLITE_OK ){