Merge branch 'auxiliary' into metadata-filtering

TODO

@@ -1,21 +1,16 @@
 # partition
 
-- UPDATE on partition key values
+- [ ] UPDATE on partition key values
   - remove previous row from chunk, insert into new one?
-- enforce column types on insert?
-- allow null values?
-- properly sqlite3_vtab_nochange / sqlite3_value_nochange handling
+- [ ] properly sqlite3_vtab_nochange / sqlite3_value_nochange handling
 
 
 # auxiliary columns
 
-- DELETE and UPDATE support
-- in xBestIndex, ensure there are no constraints on any aux column
-- enforce column types, ie STRICT?
-- NOT NULL?
-- drop aux shadow table on xDestroy
-- perf: INSERT stmt should be cached on vec0_vtab
-- perf: LEFT JOIN aux table to rowids query in vec0_cursor for rowid/point stmts, to avoid N lookup queries
+- later:
+  - NOT NULL?
+  - perf: INSERT stmt should be cached on vec0_vtab
+  - perf: LEFT JOIN aux table to rowids query in vec0_cursor for rowid/point stmts, to avoid N lookup queries
 
 # metadata filtering