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)