COPY. We need a restriction here because when the delimiter occurs as a
data character, it is emitted with a backslash, and that will only work
as desired if CopyReadAttributesText() will interpret the backslash sequence
as representing the second character literally. This is currently untrue
for 'b', 'f', 'n', 'r', 't', 'v', 'x', and octal digits. For future-proofing
and simplicity of explanation, it seems best to disallow a-z and 0-9.
We must also disallow dot, since "\." by itself would look like copy EOF.
Note: "\N" is by default the null print string, so N would also cause a
problem, but that is already tested for.
CopyAttributeOutText(), so that control characters are converted to the
C-style escape sequences even if they happen to be equal to the column
delimiter (as is true by default for tab, for example). Oversight in my
previous patch to restore pre-8.3 behavior of COPY OUT escaping. Per report
from Tomas Szepe.
< * Experiment with multi-threaded backend better resource utilization
<
< This would allow a single query to make use of multiple CPU's or
< multiple I/O channels simultaneously. One idea is to create a
< background reader that can pre-fetch sequential and index scan
< pages needed by other backends. This could be expanded to allow
< concurrent reads from multiple devices in a partitioned table.
<
> * Experiment with multi-threaded backend better resource utilization
>
> This would allow a single query to make use of multiple CPU's or
> multiple I/O channels simultaneously. One idea is to create a
> background reader that can pre-fetch sequential and index scan
> pages needed by other backends. This could be expanded to allow
> concurrent reads from multiple devices in a partitioned table.
print the index key variable or expression for that column. It was mistakenly
printing ASC/DESC/NULLS FIRST/NULLS LAST decoration too --- and not only for
the target column, but all columns. Someday we should have an option to
extract that info (and the opclass decoration as well) for a single index
column ... but today is not that day. Per bug #3829 and subsequent
discussion.
The zero-point case is sensible so far as the data structure is concerned,
so maybe we ought to allow it sometime; but right now the textual input
routines for these types don't allow it, and it seems that not all the
functions for the types are prepared to cope.
Report and patch by Merlin Moncure.
* Consider having the background writer update the transaction status
hint bits before writing out the page
Implementing this requires the background writer to have access to system
catalogs and the transaction status log.
psql's \d commands and other uses of printQuery(). Previously we would pass
these strings through gettext() and then send them to the server as literals
in the SQL query. But the code was not set up to handle doubling of quotes in
the strings, causing failure if a translation attempted to use the wrong kind
of quote marks, as indeed is now the case for (at least) the French
translation of \dFp. Another hazard was that gettext() would translate to
whatever encoding was implied by the client's LC_CTYPE setting, which might be
different from the client_encoding setting, which would probably cause the
server to reject the query as mis-encoded. The new arrangement is to send the
untranslated ASCII strings to the server, and do the translations inside
printQuery() after the query results come back. Per report from Guillaume
Lelarge and subsequent discussion.
