Hi All,<br />Consider following sequence of commands<br /><br />create type complex as (r float8, i float8);<br />
createtype quad as (c1 complex, c2 complex);<br /> create temp table quadtable(f1 int, q quad);<br /><br clear="all"
/>insertinto quadtable (f1, q.c1.r, q.c2.i) values(44,55,66);<br /><br />While parsing the INSERT query, we parse the
querywith three columns and three values in the target list, but during rewriting we combine q.c1.r and q.c2.i into a
singlecolumn in the form of FieldStore structure. In Postgres-XC, we deparse these parse trees, to be sent to other
PostgreSQLservers. The function processIndirection(), which deparses the indirections, can not handle more than one
fieldin FieldStore node.<br /><br />7344 /*<br />7345 * Print the field name. There should
onlybe one target field in<br />7346 * stored rules. There could be more than that in executable<br
/>7347 * target lists, but this function cannot be used for that case.<br /> 7348 */<br
/>7349 Assert(list_length(fstore->fieldnums) == 1);<br />7350 fieldname =
get_relid_attribute_name(typrelid,<br/>7351
linitial_int(fstore->fieldnums));<br/> 7352 if (printit)<br />7353 appendStringInfo(buf,
".%s",quote_identifier(fieldname));<br /><br />Why is this restriction here?<br /><br />The assertion is added by
commit858d1699. The notes for the commit have following paragraph related to FieldStore deparsing.<br /><br /> I
choseto represent an assignment ArrayRef as "array[subscripts] := source",<br /> which is fairly reasonable and
doesn'tomit any information. However,<br /> FieldStore is problematic because the planner will fold multiple
assignments<br/> to fields of the same composite column into one FieldStore, resulting in a<br /> structure that
ishard to understand at all, let alone display comprehensibly.<br /> So in that case I punted and just made it print
thesource expression(s).<br /><br />So, there doesn't seem to be any serious reason behind the restriction.<br /><br />
--<br />Best Wishes,<br />Ashutosh Bapat<br />EntepriseDB Corporation<br />The Enterprise Postgres Company<br /><br />
