TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="INDEX-LOCKING"
>54.4. Index Locking Considerations</A
></H1
><P
>   Index access methods must handle concurrent updates
   of the index by multiple processes.
   The core <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> system obtains
   <TT
CLASS="LITERAL"
>AccessShareLock</TT
> on the index during an index scan, and
   <TT
CLASS="LITERAL"
>RowExclusiveLock</TT
> when updating the index (including plain
   <TT
CLASS="C