Revert "Refactor CopyAttributeOut{CSV,Text}() to use a callback in COPY TO"

This reverts commit 2889fd23be56, following a discussion with Andres
Freund as this callback, being called once per attribute when sending a
relation's row, can involve a lot of indirect function calls (more
attributes to deal with means more impact).  The effects of a dispatch
at this level would become more visible when improving the per-row code
execution of COPY TO, impacting future potential performance
improvements.

Discussion: https://postgr.es/m/20240206014125.qofww7ew3dx3v3uk@awork3.anarazel.de

diff --git a/src/backend/commands/copyto.c b/src/backend/commands/copyto.c
index 52b42f8a522ef902349ad04c518215d23bc4c69c..d3dc3fc854f1437d222e581176e20aaed1dd456e 100644 (file)
--- a/src/backend/commands/copyto.c
+++ b/src/backend/commands/copyto.c
@@ -54,14 +54,6 @@ typedef enum CopyDest
        COPY_CALLBACK,                          /* to callback function */
 } CopyDest;
 
-/*
- * Per-format callback to send output representation of one attribute for
- * a `string`.  `use_quote` tracks if quotes are required in the output
- * representation.
- */
-typedef void (*CopyAttributeOut) (CopyToState cstate, const char *string,
-                                                                 bool use_quote);
-
 /*
  * This struct contains all the state variables used throughout a COPY TO
  * operation.
@@ -105,7 +97,6 @@ typedef struct CopyToStateData
        MemoryContext copycontext;      /* per-copy execution context */
 
        FmgrInfo   *out_functions;      /* lookup info for output functions */
-       CopyAttributeOut copy_attribute_out;    /* output representation callback */
        MemoryContext rowcontext;       /* per-row evaluation context */
        uint64          bytes_processed;        /* number of bytes processed so far */
 } CopyToStateData;
@@ -126,12 +117,9 @@ static const char BinarySignature[11] = "PGCOPY\n\377\r\n\0";
 static void EndCopy(CopyToState cstate);
 static void ClosePipeToProgram(CopyToState cstate);
 static void CopyOneRowTo(CopyToState cstate, TupleTableSlot *slot);
-
-/* Callbacks for copy_attribute_out */
-static void CopyAttributeOutText(CopyToState cstate, const char *string,
-                                                                bool use_quote);
+static void CopyAttributeOutText(CopyToState cstate, const char *string);
 static void CopyAttributeOutCSV(CopyToState cstate, const char *string,
-                                                               bool use_quote);
+                                                               bool use_quote, bool single_attr);
 
 /* Low-level communications functions */
 static void SendCopyBegin(CopyToState cstate);
@@ -445,15 +433,6 @@ BeginCopyTo(ParseState *pstate,
        /* Extract options from the statement node tree */
        ProcessCopyOptions(pstate, &cstate->opts, false /* is_from */ , options);
 
-       /* Set output representation callback */
-       if (!cstate->opts.binary)
-       {
-               if (cstate->opts.csv_mode)
-                       cstate->copy_attribute_out = CopyAttributeOutCSV;
-               else
-                       cstate->copy_attribute_out = CopyAttributeOutText;
-       }
-
        /* Process the source/target relation or query */
        if (rel)
        {
@@ -857,8 +836,11 @@ DoCopyTo(CopyToState cstate)
 
                                colname = NameStr(TupleDescAttr(tupDesc, attnum - 1)->attname);
 
-                               /* Ignore quotes */
-                               cstate->copy_attribute_out(cstate, colname, false);
+                               if (cstate->opts.csv_mode)
+                                       CopyAttributeOutCSV(cstate, colname, false,
+                                                                               list_length(cstate->attnumlist) == 1);
+                               else
+                                       CopyAttributeOutText(cstate, colname);
                        }
 
                        CopySendEndOfRow(cstate);
@@ -968,9 +950,12 @@ CopyOneRowTo(CopyToState cstate, TupleTableSlot *slot)
                        {
                                string = OutputFunctionCall(&out_functions[attnum - 1],
                                                                                        value);
-
-                               cstate->copy_attribute_out(cstate, string,
-                                                                                  cstate->opts.force_quote_flags[attnum - 1]);
+                               if (cstate->opts.csv_mode)
+                                       CopyAttributeOutCSV(cstate, string,
+                                                                               cstate->opts.force_quote_flags[attnum - 1],
+                                                                               list_length(cstate->attnumlist) == 1);
+                               else
+                                       CopyAttributeOutText(cstate, string);
                        }
                        else
                        {
@@ -1000,8 +985,7 @@ CopyOneRowTo(CopyToState cstate, TupleTableSlot *slot)
        } while (0)
 
 static void
-CopyAttributeOutText(CopyToState cstate, const char *string,
-                                        bool use_quote)
+CopyAttributeOutText(CopyToState cstate, const char *string)
 {
        const char *ptr;
        const char *start;
@@ -1155,7 +1139,7 @@ CopyAttributeOutText(CopyToState cstate, const char *string,
  */
 static void
 CopyAttributeOutCSV(CopyToState cstate, const char *string,
-                                       bool use_quote)
+                                       bool use_quote, bool single_attr)
 {
        const char *ptr;
        const char *start;
@@ -1163,7 +1147,6 @@ CopyAttributeOutCSV(CopyToState cstate, const char *string,
        char            delimc = cstate->opts.delim[0];
        char            quotec = cstate->opts.quote[0];
        char            escapec = cstate->opts.escape[0];
-       bool            single_attr = (list_length(cstate->attnumlist) == 1);
 
        /* force quoting if it matches null_print (before conversion!) */
        if (!use_quote && strcmp(string, cstate->opts.null_print) == 0)