Re: [HACKERS] patches for items from TODO list

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Re: [HACKERS] patches for items from TODO list

Bruce Momjian-2
Sergey Ten wrote:
> Markus,
>
> Thank you for your reply.
> We considered embedding of an XML schema first followed by data. We decided
> to stick to our current data format to make sure stateless XML parsers can
> process it as well. Would it be better to add an option to the COPY command,
> to allow embedding an XML schema, so more advanced XML parsers can take
> advantage of it?

Current CVS has a WITH CSV HEADER option.  I wonder if we should add a
HEADER option to XML to output the schema --- seems to make sense.

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  [hidden email]               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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Re: [HACKERS] patches for items from TODO list

Bruce Momjian-2
Neil Conway wrote:

> Sergey Ten wrote:
> > We think that putting it in the backend will make access from other
> > components easier.
>
> In what way?
>
> It seems to me that this can be done just as easily in a client
> application / library, without cluttering the backend with yet another
> COPY output format. It would also avoid the need to mandate a single XML
> schema -- different clients will likely have different requirements.
> Since I am skeptical of the value of this feature in the first place, I
> think it would do less damage if implemented outside the backend.

We considered putting XML in psql or libpq in the past, but the problem
is that interfaces like jdbc couldn't take advantage of it. I do think
it needs to be in the backend, and I think that is the agreement we had
in the past.

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  [hidden email]               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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Re: [HACKERS] patches for items from TODO list

Andrew Dunstan
In reply to this post by Bruce Momjian-2

I've been reviewing this patch and some of the following discussion.

First, postgresql patches are usually sent as context diffs. I don't
object to unidiffs myself, but you should do what everybody else does.

Second, it's best not to combine features in one patch. The \x escape
piece should be broken out.

I'm also a rather worried about COPY producing output which it can't
itself parse. We can read our own binary, text and CSV formats, and I
think that's a useful validation tool. I know the TODO item only
mentions output, but I believe we should rethink that. In any case, if
it's valid for us to hand XML to other programs why shouldn't we accept
it too. This is all about playing nicely in the playground.

One advantage of XML is that, being hierarchical, it can easily express
nested composites (records, arrays) in a way that our present text and
CSV formats really can't. But unless I missed something this patch
doesn't in fact do anything to break out nested composites.

Finally, I don't know if there is a standard on this, or even a
convention. What do other DBs do? I'm not keen on us just inventing our
own XML dialect for something that should after all be most useful in
data exchange.

Bottom line, much as I would like to see XML input/output, I think this
needs lots more thought and discussion.

cheers

andrew

Sergey Ten wrote:

>Hello all,
>
>Thank you to all who replied for suggestions and help. Enclosed please find
>code changes for the following items:
>- Allow COPY to understand \x as a hex byte, and
>- Add XML output to COPY
>The changes include implementation of the features as well as modification
>of the copy regression test.
>
>After a careful consideration we decided to
>- put XML implementation in the backend and
>- use XML format described below, with justification of our decision.
>
>The XML schema used by the COPY TO command was designed for ease of use and
>to avoid the problem of column names appearing in XML element names.
>XML doesn't allow spaces and punctuation in element names but Postgres does
>allow these characters in column names; therefore, a direct mapping would be
>problematic.
>
>The solution selected places the column names into attribute fields where
>any special characters they contain can be properly escaped using XML
>entities.  An additional attribute is used to distinguish null fields from
>empty ones.
>
>The example below is taken from the test suite.  It demonstrates some basic
>XML escaping in row 2.  Row 3 demonstrates the difference between an empty
>string (in col2) and a null string (in col3).  If a field is null it will
>always be empty but a field which is empty may or may not be null.
>Always check the value of the 'null' attribute to be sure when a field is
>truly null.
>
><?xml version='1.0'?>
><table>
> <row>
> <col name='col1' null='n'>Jackson, Sam</col>
> <col name='col2' null='n'>\h</col>
> </row>
> <row>
> <col name='col1' null='n'>It is &quot;perfect&quot;.</col>
> <col name='col2' null='n'>&#09;</col>
> </row>
> <row>
> <col name='col1' null='n'></col>
> <col name='col2' null='y'></col>
> </row>
></table>
>
>Please let us know if about any concerns, objections the proposed change may
>cause.
>
>Best regards,
>Jason Lucas, Sergey Ten
>SourceLabs
>
>  
>
>>-----Original Message-----
>>From: Bruce Momjian [mailto:[hidden email]]
>>Sent: Wednesday, May 11, 2005 7:11 PM
>>To: Sergey Ten
>>Cc: [hidden email]; [hidden email]
>>Subject: Re: [HACKERS] patches for items from TODO list
>>
>>Sergey Ten wrote:
>>    
>>
>>>Hello all,
>>>
>>>We would like to contribute to the Postgresql community by implementing
>>>the following items from the TODO list
>>>(http://developer.postgresql.org/todo.php):
>>>. Allow COPY to understand \x as a hex byte . Allow COPY to optionally
>>>include column headings in the first line . Add XML output to COPY
>>>
>>>The changes are straightforward and include implementation of the
>>>features as well as modification of the regression tests and
>>>      
>>>
>>documentation.
>>    
>>
>>>Before sending a diff file with the changes, we would like to know if
>>>these features have been already implemented.
>>>      
>>>
>>Please check the web site version.  Someone has already implemented
>>"Allow COPY to optionally include column headings in the first line".
>>
>>As far as XML, there has been discussion on where that should be done?
>>In the backend, libpq, or psql.  It will need discussion on hackers.  I
>>assume you have read the developer's FAQ too.
>>
>>--
>>  Bruce Momjian                        |  http://candle.pha.pa.us
>>  [hidden email]               |  (610) 359-1001
>>  +  If your life is a hard drive,     |  13 Roberts Road
>>  +  Christ can be your backup.        |  Newtown Square, Pennsylvania
>>19073
>>    
>>
>>------------------------------------------------------------------------
>>
>>Index: src/backend/commands/copy.c
>>===================================================================
>>RCS file: /projects/cvsroot/pgsql/src/backend/commands/copy.c,v
>>retrieving revision 1.244
>>diff -u -r1.244 copy.c
>>--- src/backend/commands/copy.c 7 May 2005 02:22:46 -0000 1.244
>>+++ src/backend/commands/copy.c 13 May 2005 22:21:00 -0000
>>@@ -84,6 +84,16 @@
>> EOL_CRNL
>> } EolType;
>>
>>+/*
>>+ * Represents the format of the file to be read or written
>>+ */
>>+typedef enum CopyFmt
>>+{
>>+ FMT_TXT,
>>+ FMT_BIN,
>>+ FMT_CSV,
>>+ FMT_XML
>>+} CopyFmt;
>>
>> static const char BinarySignature[11] = "PGCOPY\n\377\r\n\0";
>>
>>@@ -129,14 +139,14 @@
>> static bool line_buf_converted;
>>
>> /* non-export function prototypes */
>>-static void DoCopyTo(Relation rel, List *attnumlist, bool binary, bool oids,
>>- char *delim, char *null_print, bool csv_mode, char *quote,
>>+static void DoCopyTo(Relation rel, List *attnumlist, CopyFmt fmt, bool oids,
>>+ char *delim, char *null_print, char *quote,
>> char *escape, List *force_quote_atts, bool header_line, bool fe_copy);
>>-static void CopyTo(Relation rel, List *attnumlist, bool binary, bool oids,
>>- char *delim, char *null_print, bool csv_mode, char *quote, char *escape,
>>+static void CopyTo(Relation rel, List *attnumlist, CopyFmt fmt, bool oids,
>>+ char *delim, char *null_print, char *quote, char *escape,
>>   List *force_quote_atts, bool header_line);
>>-static void CopyFrom(Relation rel, List *attnumlist, bool binary, bool oids,
>>- char *delim, char *null_print, bool csv_mode, char *quote, char *escape,
>>+static void CopyFrom(Relation rel, List *attnumlist, CopyFmt fmt, bool oids,
>>+ char *delim, char *null_print, char *quote, char *escape,
>> List *force_notnull_atts, bool header_line);
>> static bool CopyReadLine(char * quote, char * escape);
>> static char *CopyReadAttribute(const char *delim, const char *null_print,
>>@@ -171,6 +181,11 @@
>> static void CopySendInt16(int16 val);
>> static int16 CopyGetInt16(void);
>>
>>+static int GetDecimalFromHex(char hex);
>>+
>>+static void CopyAttributeOutXML (char *colname, char *string);
>>+static void CopySendStringXML(char *string);
>>+static char *CopyGetXMLEntity(char c, char *buf);
>>
>> /*
>>  * Send copy start/stop messages for frontend copies.  These have changed
>>@@ -692,10 +707,9 @@
>> List   *attnamelist = stmt->attlist;
>> List   *attnumlist;
>> bool fe_copy = false;
>>- bool binary = false;
>> bool oids = false;
>>- bool csv_mode = false;
>>- bool        header_line = false;
>>+ bool header_line = false;
>>+ CopyFmt fmt = FMT_TXT;
>> char   *delim = NULL;
>> char   *quote = NULL;
>> char   *escape = NULL;
>>@@ -715,11 +729,11 @@
>>
>> if (strcmp(defel->defname, "binary") == 0)
>> {
>>- if (binary)
>>+ if (fmt != FMT_TXT)
>> ereport(ERROR,
>> (errcode(ERRCODE_SYNTAX_ERROR),
>> errmsg("conflicting or redundant options")));
>>- binary = intVal(defel->arg);
>>+ fmt = FMT_BIN;
>> }
>> else if (strcmp(defel->defname, "oids") == 0)
>> {
>>@@ -747,11 +761,19 @@
>> }
>> else if (strcmp(defel->defname, "csv") == 0)
>> {
>>- if (csv_mode)
>>+ if (fmt != FMT_TXT)
>> ereport(ERROR,
>> (errcode(ERRCODE_SYNTAX_ERROR),
>> errmsg("conflicting or redundant options")));
>>- csv_mode = intVal(defel->arg);
>>+ fmt = FMT_CSV;
>>+ }
>>+ else if (strcmp(defel->defname, "xml") == 0)
>>+ {
>>+ if (fmt != FMT_TXT)
>>+ ereport(ERROR,
>>+ (errcode(ERRCODE_SYNTAX_ERROR),
>>+ errmsg("conflicting or redundant options")));
>>+ fmt = FMT_XML;
>> }
>> else if (strcmp(defel->defname, "header") == 0)
>> {
>>@@ -798,29 +820,39 @@
>> defel->defname);
>> }
>>
>>- if (binary && delim)
>>+ if (fmt == FMT_BIN && delim)
>> ereport(ERROR,
>> (errcode(ERRCODE_SYNTAX_ERROR),
>> errmsg("cannot specify DELIMITER in BINARY mode")));
>>
>>- if (binary && csv_mode)
>>+ if (fmt == FMT_BIN && null_print)
>> ereport(ERROR,
>> (errcode(ERRCODE_SYNTAX_ERROR),
>>- errmsg("cannot specify CSV in BINARY mode")));
>>+ errmsg("cannot specify NULL in BINARY mode")));
>>
>>- if (binary && null_print)
>>+ if (fmt == FMT_XML && is_from)
>> ereport(ERROR,
>> (errcode(ERRCODE_SYNTAX_ERROR),
>>- errmsg("cannot specify NULL in BINARY mode")));
>>+ errmsg("XML mode is not available in COPY FROM")));
>>+
>>+ if (fmt == FMT_XML && delim)
>>+ ereport(ERROR,
>>+ (errcode(ERRCODE_SYNTAX_ERROR),
>>+ errmsg("cannot specify DELIMITER in XML mode")));
>>+
>>+ if (fmt == FMT_XML && null_print)
>>+ ereport(ERROR,
>>+ (errcode(ERRCODE_SYNTAX_ERROR),
>>+ errmsg("cannot specify NULL in XML mode")));
>>
>> /* Set defaults */
>> if (!delim)
>>- delim = csv_mode ? "," : "\t";
>>+ delim = (fmt == FMT_CSV) ? "," : "\t";
>>
>> if (!null_print)
>>- null_print = csv_mode ? "" : "\\N";
>>+ null_print = (fmt == FMT_CSV) ? "" : "\\N";
>>
>>- if (csv_mode)
>>+ if (fmt == FMT_CSV)
>> {
>> if (!quote)
>> quote = "\"";
>>@@ -835,35 +867,35 @@
>> errmsg("COPY delimiter must be a single character")));
>>
>>   /* Check header */
>>- if (!csv_mode && header_line)
>>+ if (fmt != FMT_CSV && header_line)
>> ereport(ERROR,
>> (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
>> errmsg("COPY HEADER available only in CSV mode")));
>>
>> /* Check quote */
>>- if (!csv_mode && quote != NULL)
>>+ if (fmt != FMT_CSV && quote != NULL)
>> ereport(ERROR,
>> (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
>> errmsg("COPY quote available only in CSV mode")));
>>
>>- if (csv_mode && strlen(quote) != 1)
>>+ if (fmt == FMT_CSV && strlen(quote) != 1)
>> ereport(ERROR,
>> (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
>> errmsg("COPY quote must be a single character")));
>>
>> /* Check escape */
>>- if (!csv_mode && escape != NULL)
>>+ if (fmt != FMT_CSV && escape != NULL)
>> ereport(ERROR,
>> (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
>> errmsg("COPY escape available only in CSV mode")));
>>
>>- if (csv_mode && strlen(escape) != 1)
>>+ if (fmt == FMT_CSV && strlen(escape) != 1)
>> ereport(ERROR,
>> (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
>> errmsg("COPY escape must be a single character")));
>>
>> /* Check force_quote */
>>- if (!csv_mode && force_quote != NIL)
>>+ if (fmt != FMT_CSV && force_quote != NIL)
>> ereport(ERROR,
>> (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
>> errmsg("COPY force quote available only in CSV mode")));
>>@@ -873,7 +905,7 @@
>>   errmsg("COPY force quote only available using COPY TO")));
>>
>> /* Check force_notnull */
>>- if (!csv_mode && force_notnull != NIL)
>>+ if (fmt != FMT_CSV && force_notnull != NIL)
>> ereport(ERROR,
>> (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
>>  errmsg("COPY force not null available only in CSV mode")));
>>@@ -889,7 +921,7 @@
>> errmsg("COPY delimiter must not appear in the NULL specification")));
>>
>> /* Don't allow the csv quote char to appear in the null string. */
>>- if (csv_mode && strchr(null_print, quote[0]) != NULL)
>>+ if (fmt == FMT_CSV && strchr(null_print, quote[0]) != NULL)
>> ereport(ERROR,
>> (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
>> errmsg("CSV quote character must not appear in the NULL specification")));
>>@@ -1004,7 +1036,7 @@
>> if (pipe)
>> {
>> if (whereToSendOutput == Remote)
>>- ReceiveCopyBegin(binary, list_length(attnumlist));
>>+ ReceiveCopyBegin(fmt == FMT_BIN, list_length(attnumlist));
>> else
>> copy_file = stdin;
>> }
>>@@ -1029,7 +1061,7 @@
>> errmsg("\"%s\" is a directory", filename)));
>> }
>> }
>>- CopyFrom(rel, attnumlist, binary, oids, delim, null_print, csv_mode,
>>+ CopyFrom(rel, attnumlist, fmt, oids, delim, null_print,
>> quote, escape, force_notnull_atts, header_line);
>> }
>> else
>>@@ -1093,7 +1125,7 @@
>> }
>> }
>>
>>- DoCopyTo(rel, attnumlist, binary, oids, delim, null_print, csv_mode,
>>+ DoCopyTo(rel, attnumlist, fmt, oids, delim, null_print,
>> quote, escape, force_quote_atts, header_line, fe_copy);
>> }
>>
>>@@ -1124,20 +1156,20 @@
>>  * so we don't need to plaster a lot of variables with "volatile".
>>  */
>> static void
>>-DoCopyTo(Relation rel, List *attnumlist, bool binary, bool oids,
>>- char *delim, char *null_print, bool csv_mode, char *quote,
>>+DoCopyTo(Relation rel, List *attnumlist, CopyFmt fmt, bool oids,
>>+ char *delim, char *null_print, char *quote,
>> char *escape, List *force_quote_atts, bool header_line, bool fe_copy)
>> {
>> PG_TRY();
>> {
>> if (fe_copy)
>>- SendCopyBegin(binary, list_length(attnumlist));
>>+ SendCopyBegin(fmt == FMT_BIN, list_length(attnumlist));
>>
>>- CopyTo(rel, attnumlist, binary, oids, delim, null_print, csv_mode,
>>+ CopyTo(rel, attnumlist, fmt, oids, delim, null_print,
>>   quote, escape, force_quote_atts, header_line);
>>
>> if (fe_copy)
>>- SendCopyEnd(binary);
>>+ SendCopyEnd(fmt == FMT_BIN);
>> }
>> PG_CATCH();
>> {
>>@@ -1156,8 +1188,8 @@
>>  * Copy from relation TO file.
>>  */
>> static void
>>-CopyTo(Relation rel, List *attnumlist, bool binary, bool oids,
>>-   char *delim, char *null_print, bool csv_mode, char *quote,
>>+CopyTo(Relation rel, List *attnumlist, CopyFmt fmt, bool oids,
>>+   char *delim, char *null_print, char *quote,
>>   char *escape, List *force_quote_atts, bool header_line)
>> {
>> HeapTuple tuple;
>>@@ -1187,7 +1219,7 @@
>> Oid out_func_oid;
>> bool isvarlena;
>>
>>- if (binary)
>>+ if (fmt == FMT_BIN)
>> getTypeBinaryOutputInfo(attr[attnum - 1]->atttypid,
>> &out_func_oid,
>> &isvarlena);
>>@@ -1215,7 +1247,7 @@
>>  ALLOCSET_DEFAULT_INITSIZE,
>>  ALLOCSET_DEFAULT_MAXSIZE);
>>
>>- if (binary)
>>+ if (fmt == FMT_BIN)
>> {
>> /* Generate header for a binary copy */
>> int32 tmp;
>>@@ -1233,6 +1265,14 @@
>> }
>> else
>> {
>>+ if (fmt == FMT_XML)
>>+ {
>>+ CopySendString("<?xml version='1.0'?>");
>>+ CopySendEndOfRow(false);
>>+ CopySendString("<table>");
>>+ CopySendEndOfRow(false);
>>+ }
>>+
>> /*
>> * For non-binary copy, we need to convert null_print to client
>> * encoding, because it will be sent directly with CopySendString.
>>@@ -1262,7 +1302,7 @@
>> strcmp(colname, null_print) == 0);
>> }
>>
>>- CopySendEndOfRow(binary);
>>+ CopySendEndOfRow(fmt == FMT_BIN);
>>
>> }
>> }
>>@@ -1278,7 +1318,7 @@
>> MemoryContextReset(mycontext);
>> oldcontext = MemoryContextSwitchTo(mycontext);
>>
>>- if (binary)
>>+ if (fmt == FMT_BIN)
>> {
>> /* Binary per-tuple header */
>> CopySendInt16(attr_count);
>>@@ -1294,25 +1334,34 @@
>> }
>> else
>> {
>>+ if (fmt == FMT_XML)
>>+ CopySendString("<row>");
>>+
>> /* Text format has no per-tuple header, but send OID if wanted */
>> if (oids)
>> {
>> string = DatumGetCString(DirectFunctionCall1(oidout,
>>  ObjectIdGetDatum(HeapTupleGetOid(tuple))));
>>- CopySendString(string);
>>+
>>+ if (fmt == FMT_XML)
>>+ CopyAttributeOutXML("oid", string);
>>+ else
>>+ CopySendString(string);
>>+
>> need_delim = true;
>> }
>> }
>>
>> foreach(cur, attnumlist)
>> {
>>- int attnum = lfirst_int(cur);
>>+ int attnum = lfirst_int(cur);
>> Datum value;
>> bool isnull;
>>+ char *colname = NameStr(attr[attnum - 1]->attname);
>>
>> value = heap_getattr(tuple, attnum, tupDesc, &isnull);
>>
>>- if (!binary)
>>+ if (fmt == FMT_TXT || fmt == FMT_CSV)
>> {
>> if (need_delim)
>> CopySendChar(delim[0]);
>>@@ -1321,53 +1370,71 @@
>>
>> if (isnull)
>> {
>>- if (!binary)
>>- CopySendString(null_print); /* null indicator */
>>- else
>>- CopySendInt32(-1); /* null marker */
>>+ switch (fmt)
>>+ {
>>+ case FMT_BIN:
>>+ CopySendInt32(-1); /* null marker */
>>+ break;
>>+ case FMT_XML:
>>+ CopyAttributeOutXML(colname, NULL); /* null entity */
>>+ break;
>>+ default:
>>+ CopySendString(null_print); /* null indicator */
>>+ break;
>>+ }
>>+
>> }
>> else
>> {
>>- if (!binary)
>>+ if (fmt == FMT_BIN)
>> {
>>- string = DatumGetCString(FunctionCall1(&out_functions[attnum - 1],
>>-   value));
>>- if (csv_mode)
>>- {
>>- CopyAttributeOutCSV(string, delim, quote, escape,
>>-  (strcmp(string, null_print) == 0 ||
>>-   force_quote[attnum - 1]));
>>- }
>>- else
>>- CopyAttributeOut(string, delim);
>>-
>>+ bytea *outputbytes =
>>+ DatumGetByteaP(FunctionCall1(&out_functions[attnum - 1], value));
>>+ /* We assume the result will not have been toasted */
>>+ CopySendInt32(VARSIZE(outputbytes) - VARHDRSZ);
>>+ CopySendData(VARDATA(outputbytes), VARSIZE(outputbytes) - VARHDRSZ);
>> }
>> else
>> {
>>- bytea   *outputbytes;
>>-
>>- outputbytes = DatumGetByteaP(FunctionCall1(&out_functions[attnum - 1],
>>-   value));
>>- /* We assume the result will not have been toasted */
>>- CopySendInt32(VARSIZE(outputbytes) - VARHDRSZ);
>>- CopySendData(VARDATA(outputbytes),
>>- VARSIZE(outputbytes) - VARHDRSZ);
>>+ string = DatumGetCString(FunctionCall1(&out_functions[attnum - 1], value));
>>+ switch (fmt)
>>+ {
>>+ case FMT_CSV:
>>+ CopyAttributeOutCSV(string, delim, quote, escape,
>>+ (strcmp(string, null_print) == 0
>>+ || force_quote[attnum - 1]));
>>+ break;
>>+ case FMT_XML:
>>+ CopyAttributeOutXML(colname, string);
>>+ break;
>>+ default:
>>+ CopyAttributeOut(string, delim);
>>+ break;
>>+ }
>> }
>> }
>> }
>>
>>- CopySendEndOfRow(binary);
>>+ if (fmt == FMT_XML)
>>+ CopySendString("</row>");
>>+
>>+ CopySendEndOfRow(fmt == FMT_BIN);
>>
>> MemoryContextSwitchTo(oldcontext);
>> }
>>
>> heap_endscan(scandesc);
>>
>>- if (binary)
>>+ if (fmt == FMT_BIN)
>> {
>> /* Generate trailer for a binary copy */
>> CopySendInt16(-1);
>> }
>>+ else if (fmt == FMT_XML)
>>+ {
>>+ CopySendString("</table>");
>>+ CopySendEndOfRow(false);
>>+ }
>>
>> MemoryContextDelete(mycontext);
>>
>>@@ -1464,8 +1531,8 @@
>>  * Copy FROM file to relation.
>>  */
>> static void
>>-CopyFrom(Relation rel, List *attnumlist, bool binary, bool oids,
>>- char *delim, char *null_print, bool csv_mode, char *quote,
>>+CopyFrom(Relation rel, List *attnumlist, CopyFmt fmt, bool oids,
>>+ char *delim, char *null_print, char *quote,
>> char *escape, List *force_notnull_atts, bool header_line)
>> {
>> HeapTuple tuple;
>>@@ -1549,7 +1616,7 @@
>> continue;
>>
>> /* Fetch the input function and typioparam info */
>>- if (binary)
>>+ if (fmt == FMT_BIN)
>> getTypeBinaryInputInfo(attr[attnum - 1]->atttypid,
>> &in_func_oid, &typioparams[attnum - 1]);
>> else
>>@@ -1620,7 +1687,7 @@
>> */
>> ExecBSInsertTriggers(estate, resultRelInfo);
>>
>>- if (!binary)
>>+ if (fmt != FMT_BIN)
>> file_has_oids = oids; /* must rely on user to tell us this... */
>> else
>> {
>>@@ -1663,7 +1730,7 @@
>> }
>> }
>>
>>- if (file_has_oids && binary)
>>+ if (file_has_oids && fmt == FMT_BIN)
>> {
>> getTypeBinaryInputInfo(OIDOID,
>>   &in_func_oid, &oid_typioparam);
>>@@ -1681,7 +1748,7 @@
>> /* Initialize static variables */
>> fe_eof = false;
>> eol_type = EOL_UNKNOWN;
>>- copy_binary = binary;
>>+ copy_binary = (fmt == FMT_BIN);
>> copy_relname = RelationGetRelationName(rel);
>> copy_lineno = 0;
>> copy_attname = NULL;
>>@@ -1718,14 +1785,14 @@
>> MemSet(values, 0, num_phys_attrs * sizeof(Datum));
>> MemSet(nulls, 'n', num_phys_attrs * sizeof(char));
>>
>>- if (!binary)
>>+ if (fmt != FMT_BIN)
>> {
>> CopyReadResult result = NORMAL_ATTR;
>> char   *string;
>> ListCell   *cur;
>>
>> /* Actually read the line into memory here */
>>- done = csv_mode ?
>>+ done = (fmt == FMT_CSV) ?
>> CopyReadLine(quote, escape) : CopyReadLine(NULL, NULL);
>>
>> /*
>>@@ -1776,7 +1843,7 @@
>> errmsg("missing data for column \"%s\"",
>> NameStr(attr[m]->attname))));
>>
>>- if (csv_mode)
>>+ if (fmt == FMT_CSV)
>> {
>> string = CopyReadAttributeCSV(delim, null_print, quote,
>>   escape, &result, &isnull);
>>@@ -1789,7 +1856,7 @@
>> string = CopyReadAttribute(delim, null_print,
>>   &result, &isnull);
>>
>>- if (csv_mode && isnull && force_notnull[m])
>>+ if (fmt == FMT_CSV && isnull && force_notnull[m])
>> {
>> string = null_print; /* set to NULL string */
>> isnull = false;
>>@@ -2275,6 +2342,27 @@
>> }
>>
>> /*----------
>>+ * Returns decimal value for a hexadecimal digit.
>>+*----------
>>+ */
>>+static int GetDecimalFromHex(char hex)
>>+{
>>+ if (isdigit(hex))
>>+ {
>>+ // If it is a digit
>>+ return hex - '0';
>>+ }
>>+ if (hex < 'a')
>>+ {
>>+ return hex - 'A' + 10;
>>+ }
>>+ else
>>+ {
>>+ return hex - 'a' + 10;
>>+ }
>>+}
>>+
>>+/*----------
>>  * Read the value of a single attribute, performing de-escaping as needed.
>>  *
>>  * delim is the column delimiter string (must be just one byte for now).
>>@@ -2378,6 +2466,29 @@
>> case 'v':
>> c = '\v';
>> break;
>>+ case 'x':
>>+ case 'X':
>>+ if (line_buf.cursor < line_buf.len)
>>+ {
>>+ char hexchar = line_buf.data[line_buf.cursor];
>>+ if (isxdigit(hexchar))
>>+ {
>>+ int val = GetDecimalFromHex(hexchar);
>>+ line_buf.cursor++;
>>+ if (line_buf.cursor < line_buf.len)
>>+ {
>>+ hexchar = line_buf.data[line_buf.cursor];
>>+ if (isxdigit(hexchar))
>>+ {
>>+ line_buf.cursor++;
>>+ val = (val << 4) + GetDecimalFromHex(hexchar);
>>+ }
>>+ }
>>+
>>+ c = val & 0xff;
>>+ }
>>+ }
>>+ break;
>>
>> /*
>> * in all other cases, take the char after '\'
>>@@ -2760,3 +2871,84 @@
>>
>> return attnums;
>> }
>>+
>>+/*
>>+ * Send XML representation of one attribute, with element tagging, null
>>+ * marking, and entity escaping.
>>+ */
>>+
>>+static void
>>+CopyAttributeOutXML (char *colname, char *string)
>>+{
>>+ CopySendString("<col name='");
>>+ CopySendStringXML(colname);
>>+ CopySendString("' null='");
>>+ CopySendChar((string == NULL) ? 'y' : 'n');
>>+ CopySendString("'>");
>>+
>>+ if (string != NULL)
>>+ CopySendStringXML(string);
>>+
>>+ CopySendString("</col>");
>>+}
>>+
>>+/*
>>+ * Sends a string with entity escaping.
>>+ */
>>+
>>+static void
>>+CopySendStringXML (char *string)
>>+{
>>+ char *csr;
>>+ for (csr = string; *csr; ++csr)
>>+ {
>>+ char buf[10];
>>+ char *entity = CopyGetXMLEntity(*csr, buf);
>>+ if (entity)
>>+ CopySendString(entity);
>>+ else
>>+ CopySendChar(*csr);
>>+ }
>>+}
>>+
>>+/*
>>+ * Locates or creates an XML entity for the given character.
>>+ * If that character doesn't require an entity, then the
>>+ * function returns NULL.
>>+ */
>>+
>>+static char *
>>+CopyGetXMLEntity (char c, char *buf)
>>+{
>>+ char *entity;
>>+
>>+ switch (c)
>>+ {
>>+ case '<':
>>+ entity = "&lt;";
>>+ break;
>>+ case '>':
>>+ entity = "&gt;";
>>+ break;
>>+ case '&':
>>+ entity = "&amp;";
>>+ break;
>>+ case '\'':
>>+ entity = "&apos;";
>>+ break;
>>+ case '"':
>>+ entity = "&quot;";
>>+ break;
>>+ default:
>>+ if (!isgraph(c) && c != ' ')
>>+ {
>>+ sprintf(buf, "&#%02x;", (unsigned char)c);
>>+ entity = buf;
>>+ }
>>+ else
>>+ entity = NULL;
>>+ break;
>>+ }
>>+
>>+ return entity;
>>+}
>>Index: src/backend/parser/gram.y
>>===================================================================
>>RCS file: /projects/cvsroot/pgsql/src/backend/parser/gram.y,v
>>retrieving revision 2.491
>>diff -u -r2.491 gram.y
>>--- src/backend/parser/gram.y 7 May 2005 02:22:46 -0000 2.491
>>+++ src/backend/parser/gram.y 13 May 2005 22:21:01 -0000
>>@@ -413,6 +413,8 @@
>>
>> WHEN WHERE WITH WITHOUT WORK WRITE
>>
>>+ XML
>>+
>> YEAR_P
>>
>> ZONE
>>@@ -1448,6 +1450,10 @@
>> {
>> $$ = makeDefElem("header", (Node *)makeInteger(TRUE));
>> }
>>+ | XML
>>+ {
>>+ $$ = makeDefElem("xml", (Node *)makeInteger(TRUE));
>>+ }
>> | QUOTE opt_as Sconst
>> {
>> $$ = makeDefElem("quote", (Node *)makeString($3));
>>Index: src/backend/parser/keywords.c
>>===================================================================
>>RCS file: /projects/cvsroot/pgsql/src/backend/parser/keywords.c,v
>>retrieving revision 1.155
>>diff -u -r1.155 keywords.c
>>--- src/backend/parser/keywords.c 7 May 2005 02:22:47 -0000 1.155
>>+++ src/backend/parser/keywords.c 13 May 2005 22:21:01 -0000
>>@@ -342,6 +342,7 @@
>> {"without", WITHOUT},
>> {"work", WORK},
>> {"write", WRITE},
>>+ {"xml", XML},
>> {"year", YEAR_P},
>> {"zone", ZONE},
>> };
>>Index: src/test/regress/expected/copy2.out
>>===================================================================
>>RCS file: /projects/cvsroot/pgsql/src/test/regress/expected/copy2.out,v
>>retrieving revision 1.21
>>diff -u -r1.21 copy2.out
>>--- src/test/regress/expected/copy2.out 13 May 2005 06:33:40 -0000 1.21
>>+++ src/test/regress/expected/copy2.out 13 May 2005 22:21:01 -0000
>>@@ -194,6 +194,28 @@
>> --test that we read consecutive LFs properly
>> CREATE TEMP TABLE testnl (a int, b text, c int);
>> COPY testnl FROM stdin CSV;
>>-DROP TABLE x, y;
>>+CREATE TABLE z (
>>+ col1 text,
>>+ col2 text
>>+);
>>+COPY z from stdin;
>>+COPY z TO stdout;
>>+Jackson, Sam \\h
>>+ABC \\\\\t
>>+It is "perfect". \t
>>+ NULL
>>+COPY z TO stdout WITH CSV;
>>+"Jackson, Sam",\h
>>+ABC,\\
>>+"It is ""perfect"".",
>>+"",NULL
>>+COPY y TO stdout WITH XML;
>>+<?xml version='1.0'?>
>>+<table>
>>+<row><col name='col1' null='n'>Jackson, Sam</col><col name='col2' null='n'>\h</col></row>
>>+<row><col name='col1' null='n'>It is &quot;perfect&quot;.</col><col name='col2' null='n'>&#09;</col></row>
>>+<row><col name='col1' null='n'></col><col name='col2' null='y'></col></row>
>>+</table>
>>+DROP TABLE x, y, z;
>> DROP FUNCTION fn_x_before();
>> DROP FUNCTION fn_x_after();
>>Index: src/test/regress/sql/copy2.sql
>>===================================================================
>>RCS file: /projects/cvsroot/pgsql/src/test/regress/sql/copy2.sql,v
>>retrieving revision 1.12
>>diff -u -r1.12 copy2.sql
>>--- src/test/regress/sql/copy2.sql 13 May 2005 06:33:40 -0000 1.12
>>+++ src/test/regress/sql/copy2.sql 13 May 2005 22:21:01 -0000
>>@@ -139,7 +139,22 @@
>> inside",2
>> \.
>>
>>+CREATE TABLE z (
>>+ col1 text,
>>+ col2 text
>>+);
>>
>>-DROP TABLE x, y;
>>+COPY z from stdin;
>>+Jackson, Sam \\h
>>+\x41\x42\x43\xa0\x1 \x5c\x5c\x9
>>+It is "perfect". \t
>>+ NULL
>>+\.
>>+
>>+COPY z TO stdout;
>>+COPY z TO stdout WITH CSV;
>>+COPY y TO stdout WITH XML;
>>+
>>+DROP TABLE x, y, z;
>> DROP FUNCTION fn_x_before();
>> DROP FUNCTION fn_x_after();
>>    
>>
>>------------------------------------------------------------------------
>>
>>
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>>
>>               http://archives.postgresql.org
>>    
>>

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Re: [HACKERS] patches for items from TODO list

Neil Conway-2
In reply to this post by Bruce Momjian-2
Bruce Momjian wrote:
> We considered putting XML in psql or libpq in the past, but the problem
> is that interfaces like jdbc couldn't take advantage of it.

Well, you could implement it as a C UDF and use SPI. Or write it as a C
client library, and use JNI. Or just provide a Java implementation --
it's not like the COPY -> XML transformation is very complex.

To restate the case:

- I don't see how this feature is useful. Perhaps I'm mistaken, but I
don't think there's a lot of user demand for it (feel free to
demonstrate the contrary)

- The COPY -> XML transformation is trivial -- it would be easy for
clients to roll their own. At the same time, there is no standard or
canonical XML representation for COPY output, and I can easily imagine
different clients needing different representations. So there is limited
value in providing a single, inflexible backend implementation.

- There's no need for it to be in the backend, anyway. Perhaps if there
were overwhelming demand for this functionality, we would need to
provide it for all client libraries and the easiest solution would be to
put it in the backend, but I don't think that's the case.

If people really think XML COPY output mode is useful, why not implement
it client-side first and host it on pgfoundry? If lots of people are
using the client-side code, we can consider moving it into the core
distribution or the backend itself at that point.

-Neil

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Re: [HACKERS] patches for items from TODO list

Bruce Momjian-2
Neil Conway wrote:

> Bruce Momjian wrote:
> > We considered putting XML in psql or libpq in the past, but the problem
> > is that interfaces like jdbc couldn't take advantage of it.
>
> Well, you could implement it as a C UDF and use SPI. Or write it as a C
> client library, and use JNI. Or just provide a Java implementation --
> it's not like the COPY -> XML transformation is very complex.
>
> To restate the case:
>
> - I don't see how this feature is useful. Perhaps I'm mistaken, but I
> don't think there's a lot of user demand for it (feel free to
> demonstrate the contrary)
>
> - The COPY -> XML transformation is trivial -- it would be easy for
> clients to roll their own. At the same time, there is no standard or
> canonical XML representation for COPY output, and I can easily imagine
> different clients needing different representations. So there is limited
> value in providing a single, inflexible backend implementation.
>
> - There's no need for it to be in the backend, anyway. Perhaps if there
> were overwhelming demand for this functionality, we would need to
> provide it for all client libraries and the easiest solution would be to
> put it in the backend, but I don't think that's the case.
>
> If people really think XML COPY output mode is useful, why not implement
> it client-side first and host it on pgfoundry? If lots of people are
> using the client-side code, we can consider moving it into the core
> distribution or the backend itself at that point.

All I can say is that we rejected an XML in the client patch a long time
ago and the discussion was that it belongs in the backend so everyone
can use it.  I don't use XML myself so I have no opinion.  We need
people who need XML output to comment in this thread.

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  [hidden email]               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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Re: [HACKERS] patches for items from TODO list

Josh berkus
In reply to this post by Neil Conway-2
Folks,

> - The COPY -> XML transformation is trivial -- it would be easy for
> clients to roll their own. At the same time, there is no standard or
> canonical XML representation for COPY output, and I can easily imagine
> different clients needing different representations. So there is limited
> value in providing a single, inflexible backend implementation.

I'm going to second Neil here.   This feature becomes useful *only* when there
is a certified or de-facto universal standard XML representation for database
data.   Then I could see a case for it.  But there isn't.  

Feel free to throw it on pgFoundry, though.

--
Josh Berkus
Aglio Database Solutions
San Francisco

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Re: [HACKERS] patches for items from TODO list

Tom Lane-2
Josh Berkus <[hidden email]> writes:
> I'm going to second Neil here.

I think the same --- given the points about lack of standardization,
it seems premature to put this into the backend.  I'd be for it if
there were a clear standard, but ...

                        regards, tom lane

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Re: [HACKERS] patches for items from TODO list

Christopher Kings-Lynne
In reply to this post by Josh berkus
> I'm going to second Neil here.   This feature becomes useful *only* when there
> is a certified or de-facto universal standard XML representation for database
> data.   Then I could see a case for it.  But there isn't.  

We've done it in phpPgAdmin (we made up our own standard), and a couple
of people use it.  I also do not think that it should be in the backend
until there is a standard.  Here is what phpPgAdmin produces (note NULL
handling):

<?xml version="1.0" encoding="UTF-8" ?>
<data>
        <header>
                <column name="feature_id" type="varchar" />
                <column name="feature_name" type="varchar" />
                <column name="is_supported" type="varchar" />
                <column name="is_verified_by" type="varchar" />
                <column name="comments" type="varchar" />
        </header>
        <records>
                <row>
                        <column name="feature_id">PKG000</column>
                        <column name="feature_name">Core</column>
                        <column name="is_supported">NO</column>
                        <column name="is_verified_by" null="null"></column>
                        <column name="comments" null="null"></column>
                </row>
                <row>
                        <column name="feature_id">PKG001</column>
                        <column name="feature_name">Enhanced datetime facilities</column>
                        <column name="is_supported">YES</column>
                        <column name="is_verified_by" null="null"></column>
                        <column name="comments" null="null"></column>
                </row>
                <row>
                        <column name="feature_id">PKG002</column>
                        <column name="feature_name">Enhanced integrity management</column>
                        <column name="is_supported">NO</column>
                        <column name="is_verified_by" null="null"></column>
                        <column name="comments" null="null"></column>
                </row>
                <row>
                        <column name="feature_id">PKG003</column>
                        <column name="feature_name">OLAP facilities</column>
                        <column name="is_supported">NO</column>
                        <column name="is_verified_by" null="null"></column>
                        <column name="comments" null="null"></column>
                </row>
                <row>
                        <column name="feature_id">PKG004</column>
                        <column name="feature_name">PSM</column>
                        <column name="is_supported">NO</column>
                        <column name="is_verified_by" null="null"></column>
                        <column name="comments">PL/pgSQL is similar.</column>
                </row>
                <row>
                        <column name="feature_id">PKG005</column>
                        <column name="feature_name">CLI</column>
                        <column name="is_supported">NO</column>
                        <column name="is_verified_by" null="null"></column>
                        <column name="comments">ODBC is similar.</column>
                </row>
                <row>
                        <column name="feature_id">PKG006</column>
                        <column name="feature_name">Basic object support</column>
                        <column name="is_supported">NO</column>
                        <column name="is_verified_by" null="null"></column>
                        <column name="comments" null="null"></column>
                </row>
                <row>
                        <column name="feature_id">PKG007</column>
                        <column name="feature_name">Enhanced object support</column>
                        <column name="is_supported">NO</column>
                        <column name="is_verified_by" null="null"></column>
                        <column name="comments" null="null"></column>
                </row>
                <row>
                        <column name="feature_id">PKG008</column>
                        <column name="feature_name">Active database</column>
                        <column name="is_supported">NO</column>
                        <column name="is_verified_by" null="null"></column>
                        <column name="comments" null="null"></column>
                </row>
                <row>
                        <column name="feature_id">PKG010</column>
                        <column name="feature_name">OLAP</column>
                        <column name="is_supported">NO</column>
                        <column name="is_verified_by" null="null"></column>
                        <column name="comments">NO</column>
                </row>
        </records>
</data>

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Re: [HACKERS] patches for items from TODO list

Andrew Dunstan

minor nit: the null attribute should take XMLSchema boolean type values:
{true, false, 1, 0}

More importantly, how do you handle array or record type fields? If they
are just opaque text I don't think that's what I at least would want
from XML output routines.

cheers

andrew

Christopher Kings-Lynne wrote:

>> I'm going to second Neil here.   This feature becomes useful *only*
>> when there is a certified or de-facto universal standard XML
>> representation for database data.   Then I could see a case for it.  
>> But there isn't.  
>
>
> We've done it in phpPgAdmin (we made up our own standard), and a
> couple of people use it.  I also do not think that it should be in the
> backend until there is a standard.  Here is what phpPgAdmin produces
> (note NULL handling):
>
> <?xml version="1.0" encoding="UTF-8" ?>
> <data>
>     <header>
>         <column name="feature_id" type="varchar" />
>         <column name="feature_name" type="varchar" />
>         <column name="is_supported" type="varchar" />
>         <column name="is_verified_by" type="varchar" />
>         <column name="comments" type="varchar" />
>     </header>
>     <records>
>         <row>
>             <column name="feature_id">PKG000</column>
>             <column name="feature_name">Core</column>
>             <column name="is_supported">NO</column>
>             <column name="is_verified_by" null="null"></column>
>             <column name="comments" null="null"></column>
>         </row>
>         <row>
>             <column name="feature_id">PKG001</column>
>             <column name="feature_name">Enhanced datetime
> facilities</column>
>             <column name="is_supported">YES</column>
>             <column name="is_verified_by" null="null"></column>
>             <column name="comments" null="null"></column>
>         </row>
>         <row>
>             <column name="feature_id">PKG002</column>
>             <column name="feature_name">Enhanced integrity
> management</column>
>             <column name="is_supported">NO</column>
>             <column name="is_verified_by" null="null"></column>
>             <column name="comments" null="null"></column>
>         </row>
>         <row>
>             <column name="feature_id">PKG003</column>
>             <column name="feature_name">OLAP facilities</column>
>             <column name="is_supported">NO</column>
>             <column name="is_verified_by" null="null"></column>
>             <column name="comments" null="null"></column>
>         </row>
>         <row>
>             <column name="feature_id">PKG004</column>
>             <column name="feature_name">PSM</column>
>             <column name="is_supported">NO</column>
>             <column name="is_verified_by" null="null"></column>
>             <column name="comments">PL/pgSQL is similar.</column>
>         </row>
>         <row>
>             <column name="feature_id">PKG005</column>
>             <column name="feature_name">CLI</column>
>             <column name="is_supported">NO</column>
>             <column name="is_verified_by" null="null"></column>
>             <column name="comments">ODBC is similar.</column>
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>             <column name="feature_name">Basic object support</column>
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>             <column name="comments">NO</column>
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> </data>
>
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Re: [HACKERS] patches for items from TODO list

Bruce Momjian-2
In reply to this post by Josh berkus

I have removed the XML TODO item:

        * Add XML output to pg_dump and COPY
       
          We already allow XML to be stored in the database, and XPath queries
          can be used on that data using /contrib/xml2. It also supports XSLT
          transformations.

---------------------------------------------------------------------------

Josh Berkus wrote:

> Folks,
>
> > - The COPY -> XML transformation is trivial -- it would be easy for
> > clients to roll their own. At the same time, there is no standard or
> > canonical XML representation for COPY output, and I can easily imagine
> > different clients needing different representations. So there is limited
> > value in providing a single, inflexible backend implementation.
>
> I'm going to second Neil here.   This feature becomes useful *only* when there
> is a certified or de-facto universal standard XML representation for database
> data.   Then I could see a case for it.  But there isn't.  
>
> Feel free to throw it on pgFoundry, though.
>
> --
> Josh Berkus
> Aglio Database Solutions
> San Francisco
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--
  Bruce Momjian                        |  http://candle.pha.pa.us
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