Fix typos and duplicate words

This fixes various typos, duplicated words, and tiny bits of whitespace
mainly in code comments but also in docs.

Author: Daniel Gustafsson <daniel@yesql.se>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Alexander Lakhin <exclusion@gmail.com>
Author: David Rowley <dgrowleyml@gmail.com>
Author: Nazir Bilal Yavuz <byavuz81@gmail.com>
Discussion: https://postgr.es/m/3F577953-A29E-4722-98AD-2DA9EFF2CBB8@yesql.se

Author: danielgustafsson

contrib/amcheck/expected/check_btree.out

@@ -2,7 +2,7 @@ CREATE TABLE bttest_a(id int8);
 CREATE TABLE bttest_b(id int8);
 CREATE TABLE bttest_multi(id int8, data int8);
 CREATE TABLE delete_test_table (a bigint, b bigint, c bigint, d bigint);
--- Stabalize tests
+-- Stabilize tests
 ALTER TABLE bttest_a SET (autovacuum_enabled = false);
 ALTER TABLE bttest_b SET (autovacuum_enabled = false);
 ALTER TABLE bttest_multi SET (autovacuum_enabled = false);

contrib/amcheck/sql/check_btree.sql

@@ -3,7 +3,7 @@ CREATE TABLE bttest_b(id int8);
 CREATE TABLE bttest_multi(id int8, data int8);
 CREATE TABLE delete_test_table (a bigint, b bigint, c bigint, d bigint);
 
--- Stabalize tests
+-- Stabilize tests
 ALTER TABLE bttest_a SET (autovacuum_enabled = false);
 ALTER TABLE bttest_b SET (autovacuum_enabled = false);
 ALTER TABLE bttest_multi SET (autovacuum_enabled = false);

contrib/amcheck/verify_nbtree.c

@@ -3036,7 +3036,7 @@ bt_normalize_tuple(BtreeCheckState *state, IndexTuple itup)
 	 * In the heap, tuples may contain short varlena datums with both 1B
 	 * header and 4B headers.  But the corresponding index tuple should always
 	 * have such varlena's with 1B headers.  So, if there is a short varlena
-	 * with 4B header, we need to convert it for for fingerprinting.
+	 * with 4B header, we need to convert it for fingerprinting.
 	 *
 	 * Note that we rely on deterministic index_form_tuple() TOAST compression
 	 * of normalized input.

doc/src/sgml/maintenance.sgml

@@ -802,7 +802,7 @@ HINT:  Execute a database-wide VACUUM in that database.
     <para>
      Similar to the XID case, if autovacuum fails to clear old MXIDs from a table, the
      system will begin to emit warning messages when the database's oldest MXIDs reach forty
-     million transactions from the wraparound point.  And, just as an the XID case, if these
+     million transactions from the wraparound point.  And, just as in the XID case, if these
      warnings are ignored, the system will refuse to generate new MXIDs once there are fewer
      than three million left until wraparound.
     </para>

doc/src/sgml/meson.build

@@ -207,7 +207,7 @@ if docs_dep.found()
   alias_target('man', man)
   alias_target('install-man', install_doc_man)
 
-  # built and installed as part of the the docs target
+  # built and installed as part of the docs target
   installdocs += install_doc_man
   docs += man
 endif

src/backend/access/gin/ginbtree.c

@@ -766,7 +766,7 @@ ginFinishSplit(GinBtree btree, GinBtreeStack *stack, bool freestack,
 /*
  * An entry point to ginFinishSplit() that is used when we stumble upon an
  * existing incompletely split page in the tree, as opposed to completing a
- * split that we just made outselves. The difference is that stack->buffer may
+ * split that we just made ourselves. The difference is that stack->buffer may
  * be merely share-locked on entry, and will be upgraded to exclusive mode.
  *
  * Note: Upgrading the lock momentarily releases it. Doing that in a scan

src/backend/access/heap/pruneheap.c

@@ -33,7 +33,7 @@
 typedef struct
 {
 	/*-------------------------------------------------------
-	 * Arguments passed to heap_page_and_freeze()
+	 * Arguments passed to heap_page_prune_and_freeze()
 	 *-------------------------------------------------------
 	 */
 
@@ -306,7 +306,7 @@ heap_page_prune_opt(Relation relation, Buffer buffer)
  * If the HEAP_PRUNE_FREEZE option is set, we will also freeze tuples if it's
  * required in order to advance relfrozenxid / relminmxid, or if it's
  * considered advantageous for overall system performance to do so now.  The
- * 'cutoffs', 'presult', 'new_refrozen_xid' and 'new_relmin_mxid' arguments
+ * 'cutoffs', 'presult', 'new_relfrozen_xid' and 'new_relmin_mxid' arguments
  * are required when freezing.  When HEAP_PRUNE_FREEZE option is set, we also
  * set presult->all_visible and presult->all_frozen on exit, to indicate if
  * the VM bits can be set.  They are always set to false when the
@@ -337,7 +337,7 @@ heap_page_prune_opt(Relation relation, Buffer buffer)
  * off_loc is the offset location required by the caller to use in error
  * callback.
  *
- * new_relfrozen_xid and new_relmin_xid must provided by the caller if the
+ * new_relfrozen_xid and new_relmin_mxid must provided by the caller if the
  * HEAP_PRUNE_FREEZE option is set.  On entry, they contain the oldest XID and
  * multi-XID seen on the relation so far.  They will be updated with oldest
  * values present on the page after pruning.  After processing the whole

src/backend/access/nbtree/nbtutils.c

@@ -1756,7 +1756,7 @@ _bt_start_prim_scan(IndexScanDesc scan, ScanDirection dir)
  *
  * (The rules are the same for backwards scans, except that the operators are
  * flipped: just replace the precondition's >= operator with a <=, and the
- * postcondition's <= operator with with a >=.  In other words, just swap the
+ * postcondition's <= operator with a >=.  In other words, just swap the
  * precondition with the postcondition.)
  *
  * We also deal with "advancing" non-required arrays here.  Callers whose
@@ -4133,7 +4133,7 @@ _bt_checkkeys_look_ahead(IndexScanDesc scan, BTReadPageState *pstate,
 	else
 	{
 		/*
-		 * Failure -- "ahead" tuple is too far ahead (we were too aggresive).
+		 * Failure -- "ahead" tuple is too far ahead (we were too aggressive).
 		 *
 		 * Reset the number of rechecks, and aggressively reduce the target
 		 * distance (we're much more aggressive here than we were when the

src/backend/access/rmgrdesc/xactdesc.c

@@ -25,7 +25,7 @@
  * Parse the WAL format of an xact commit and abort records into an easier to
  * understand format.
  *
- * This routines are in xactdesc.c because they're accessed in backend (when
+ * These routines are in xactdesc.c because they're accessed in backend (when
  * replaying WAL) and frontend (pg_waldump) code. This file is the only xact
  * specific one shared between both. They're complicated enough that
  * duplication would be bothersome.

src/backend/catalog/pg_constraint.c

@@ -1668,7 +1668,7 @@ DeconstructFkConstraintRow(HeapTuple tuple, int *numfks,
 }
 
 /*
- * FindFkPeriodOpers -
+ * FindFKPeriodOpers -
  *
  * Looks up the operator oids used for the PERIOD part of a temporal foreign key.
  * The opclass should be the opclass of that PERIOD element.