diff options
Diffstat (limited to 'src/include/nodes/plannodes.h')
| -rw-r--r-- | src/include/nodes/plannodes.h | 37 |
1 files changed, 26 insertions, 11 deletions
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h index c63492fa0be..9313292222a 100644 --- a/src/include/nodes/plannodes.h +++ b/src/include/nodes/plannodes.h @@ -479,32 +479,46 @@ typedef struct WorkTableScan * fdw_exprs and fdw_private are both under the control of the foreign-data * wrapper, but fdw_exprs is presumed to contain expression trees and will * be post-processed accordingly by the planner; fdw_private won't be. - * An optional fdw_ps_tlist is used to map a reference to an attribute of - * underlying relation(s) onto a pair of INDEX_VAR and alternative varattno. - * When fdw_ps_tlist is used, this represents a remote join, and the FDW - * is responsible for setting this field to an appropriate value. - * Note that everything in above lists must be copiable by copyObject(). + * Note that everything in both lists must be copiable by copyObject(). * One way to store an arbitrary blob of bytes is to represent it as a bytea * Const. Usually, though, you'll be better off choosing a representation * that can be dumped usefully by nodeToString(). + * + * fdw_scan_tlist is a targetlist describing the contents of the scan tuple + * returned by the FDW; it can be NIL if the scan tuple matches the declared + * rowtype of the foreign table, which is the normal case for a simple foreign + * table scan. (If the plan node represents a foreign join, fdw_scan_tlist + * is required since there is no rowtype available from the system catalogs.) + * When fdw_scan_tlist is provided, Vars in the node's tlist and quals must + * have varno INDEX_VAR, and their varattnos correspond to resnos in the + * fdw_scan_tlist (which are also column numbers in the actual scan tuple). + * fdw_scan_tlist is never actually executed; it just holds expression trees + * describing what is in the scan tuple's columns. + * + * When the plan node represents a foreign join, scan.scanrelid is zero and + * fs_relids must be consulted to identify the join relation. (fs_relids + * is valid for simple scans as well, but will always match scan.scanrelid.) * ---------------- */ typedef struct ForeignScan { Scan scan; - Oid fdw_handler; /* OID of FDW handler */ + Oid fs_server; /* OID of foreign server */ List *fdw_exprs; /* expressions that FDW may evaluate */ - List *fdw_ps_tlist; /* tlist, if replacing a join */ List *fdw_private; /* private data for FDW */ - Bitmapset *fdw_relids; /* RTIs generated by this scan */ + List *fdw_scan_tlist; /* optional tlist describing scan tuple */ + Bitmapset *fs_relids; /* RTIs generated by this scan */ bool fsSystemCol; /* true if any "system column" is needed */ } ForeignScan; /* ---------------- * CustomScan node * - * The comments for ForeignScan's fdw_exprs, fdw_varmap and fdw_private fields - * apply equally to custom_exprs, custom_ps_tlist and custom_private. + * The comments for ForeignScan's fdw_exprs, fdw_private, fdw_scan_tlist, + * and fs_relids fields apply equally to CustomScan's custom_exprs, + * custom_private, custom_scan_tlist, and custom_relids fields. The + * convention of setting scan.scanrelid to zero for joins applies as well. + * * Note that since Plan trees can be copied, custom scan providers *must* * fit all plan data they need into those fields; embedding CustomScan in * a larger struct will not work. @@ -528,8 +542,9 @@ typedef struct CustomScan Scan scan; uint32 flags; /* mask of CUSTOMPATH_* flags, see relation.h */ List *custom_exprs; /* expressions that custom code may evaluate */ - List *custom_ps_tlist;/* tlist, if replacing a join */ List *custom_private; /* private data for custom code */ + List *custom_scan_tlist; /* optional tlist describing scan + * tuple */ Bitmapset *custom_relids; /* RTIs generated by this scan */ const CustomScanMethods *methods; } CustomScan; |