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Bugfixing for mysql_fdw #239

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Bugfixing for mysql_fdw #239

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1152ff0
Support Subscripting Array syntax
Mar 28, 2022
e4cc9ff
Not pushdown system column instead of raise error
Mar 29, 2022
4d42bba
Do not allocate when natts is 0
Mar 29, 2022
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251 changes: 184 additions & 67 deletions deparse.c
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Original file line number Diff line number Diff line change
Expand Up @@ -112,7 +112,7 @@ static void mysql_deparse_param(Param *node, deparse_expr_cxt *context);
#if PG_VERSION_NUM < 120000
static void mysql_deparse_array_ref(ArrayRef *node, deparse_expr_cxt *context);
#else
static void mysql_deparse_array_ref(SubscriptingRef *node,
static void mysql_deparse_subscripting_ref(SubscriptingRef *node,
deparse_expr_cxt *context);
#endif
static void mysql_deparse_func_expr(FuncExpr *node, deparse_expr_cxt *context);
Expand Down Expand Up @@ -549,47 +549,130 @@ mysql_deparse_column_ref(StringInfo buf, int varno, int varattno,
PlannerInfo *root, bool qualify_col)
{
RangeTblEntry *rte;
char *colname = NULL;
List *options;
ListCell *lc;

/* varno must not be any of OUTER_VAR, INNER_VAR and INDEX_VAR. */
Assert(!IS_SPECIAL_VARNO(varno));

/* Get RangeTblEntry from array in PlannerInfo. */
rte = planner_rt_fetch(varno, root);

/*
* If it's a column of a foreign table, and it has the column_name FDW
* option, use that value.
*/
options = GetForeignColumnOptions(rte->relid, varattno);
foreach(lc, options)
/* We not support fetching any system attributes from remote side */
if (varattno < 0)
{
DefElem *def = (DefElem *) lfirst(lc);
/*
* All other system attributes are fetched as 0, except for table OID
* and ctid, table OID is fetched as the local table OID, ctid is
* fectch as invalid value. However, we must be careful; the table
* could be beneath an outer join, in which case it must go to NULL
* whenever the rest of the row does.
*/
char fetchval[32];

if (strcmp(def->defname, "column_name") == 0)
if (varattno == TableOidAttributeNumber)
{
colname = defGetString(def);
break;
/*
* table OID is fetched as the local table OID
*/
pg_snprintf(fetchval, sizeof(fetchval), "%u", rte->relid);
}
else if (varattno == SelfItemPointerAttributeNumber)
{
/*
* ctid is fetched as '(4294967295,0)' ~ (0xFFFFFFFF, 0) (invalid
* value), which is default value of tupleSlot->tts_tid after run
* ExecClearTuple.
*/
pg_snprintf(fetchval, sizeof(fetchval), "'(%u,%u)'",
InvalidBlockNumber,
InvalidOffsetNumber);
}
else
{
/* other system attributes are fetched as 0 */
pg_snprintf(fetchval, sizeof(fetchval), "%u", 0);
}

appendStringInfo(buf, "%s", fetchval);
}
else if (varattno == 0)
{
/* Whole row reference */
Relation rel;
Bitmapset *attrs_used;

/*
* If it's a column of a regular table or it doesn't have column_name
* FDW option, use attribute name.
*/
if (colname == NULL)
/* Required only to be passed down to deparseTargetList(). */
List *retrieved_attrs;

/*
* The lock on the relation will be held by upper callers, so it's
* fine to open it with no lock here.
*/
rel = table_open(rte->relid, NoLock);

/*
* The local name of the foreign table can not be recognized by the
* foreign server and the table it references on foreign server might
* have different column ordering or different columns than those
* declared locally. Hence we have to deparse whole-row reference as
* ROW(columns referenced locally). Construct this by deparsing a
* "whole row" attribute.
*/
attrs_used = bms_add_member(NULL,
0 - FirstLowInvalidHeapAttributeNumber);

/*
* In case the whole-row reference is under an outer join then it has
* to go NULL whenever the rest of the row goes NULL. Deparsing a join
* query would always involve multiple relations, thus qualify_col
* would be true.
*/

mysql_deparse_target_list(buf, root, varno, rel, attrs_used,
&retrieved_attrs);

table_close(rel, NoLock);
bms_free(attrs_used);
}
else
{
char *colname = NULL;
List *options;
ListCell *lc;

/* varno must not be any of OUTER_VAR, INNER_VAR and INDEX_VAR. */
Assert(!IS_SPECIAL_VARNO(varno));

/*
* If it's a column of a foreign table, and it has the column_name FDW
* option, use that value.
*/
options = GetForeignColumnOptions(rte->relid, varattno);
foreach(lc, options)
{
DefElem *def = (DefElem *) lfirst(lc);

if (strcmp(def->defname, "column_name") == 0)
{
colname = defGetString(def);
break;
}
}

/*
* If it's a column of a regular table or it doesn't have column_name
* FDW option, use attribute name.
*/
if (colname == NULL)
#if PG_VERSION_NUM >= 110000
colname = get_attname(rte->relid, varattno, false);
colname = get_attname(rte->relid, varattno, false);
#else
colname = get_relid_attribute_name(rte->relid, varattno);
colname = get_relid_attribute_name(rte->relid, varattno);
#endif
if (qualify_col)
ADD_REL_QUALIFIER(buf, varno);

if (qualify_col)
ADD_REL_QUALIFIER(buf, varno);

appendStringInfoString(buf, mysql_quote_identifier(colname, '`'));
appendStringInfoString(buf, mysql_quote_identifier(colname, '`'));
}
}

static void
Expand Down Expand Up @@ -679,7 +762,7 @@ deparseExpr(Expr *node, deparse_expr_cxt *context)
mysql_deparse_array_ref((ArrayRef *) node, context);
#else
case T_SubscriptingRef:
mysql_deparse_array_ref((SubscriptingRef *) node, context);
mysql_deparse_subscripting_ref((SubscriptingRef *) node, context);
#endif
break;
case T_FuncExpr:
Expand Down Expand Up @@ -1003,53 +1086,41 @@ mysql_deparse_param(Param *node, deparse_expr_cxt *context)
*/
static void
#if PG_VERSION_NUM < 120000
mysql_deparse_array_ref(ArrayRef *node, deparse_expr_cxt *context)
mysql_deparse_array_ref(ArrayRef * node, deparse_expr_cxt *context)
#else
mysql_deparse_array_ref(SubscriptingRef *node, deparse_expr_cxt *context)
mysql_deparse_subscripting_ref(SubscriptingRef *node, deparse_expr_cxt *context)
#endif
{
StringInfo buf = context->buf;
ListCell *lowlist_item;
ListCell *uplist_item;
ListCell *lc;
StringInfo buf = context->buf;
bool first = true;
ArrayExpr *array_expr = (ArrayExpr *) node->refexpr;

/* Always parenthesize the expression. */
appendStringInfoChar(buf, '(');
/* Not support slice function, which is excluded in pushdown checking */
Assert(node->reflowerindexpr == NULL);
Assert(node->refupperindexpr != NULL);

/*
* Deparse referenced array expression first. If that expression includes
* a cast, we have to parenthesize to prevent the array subscript from
* being taken as typename decoration. We can avoid that in the typical
* case of subscripting a Var, but otherwise do it.
*/
if (IsA(node->refexpr, Var))
deparseExpr(node->refexpr, context);
else
{
appendStringInfoChar(buf, '(');
deparseExpr(node->refexpr, context);
appendStringInfoChar(buf, ')');
}
/* Transform array subscripting to ELT(index number, str1, str2, ...) */
appendStringInfoString(buf, "ELT(");

/* Deparse subscript expressions. */
lowlist_item = list_head(node->reflowerindexpr); /* could be NULL */
foreach(uplist_item, node->refupperindexpr)
/* Append index number of ELT() expression */
uplist_item = list_head(node->refupperindexpr);
deparseExpr(lfirst(uplist_item), context);
appendStringInfoString(buf, ", ");

/* Deparse Array Expression in form of ELT syntax */
foreach(lc, array_expr->elements)
{
appendStringInfoChar(buf, '[');
if (lowlist_item)
{
deparseExpr(lfirst(lowlist_item), context);
appendStringInfoChar(buf, ':');
#if PG_VERSION_NUM < 130000
lowlist_item = lnext(lowlist_item);
#else
lowlist_item = lnext(node->reflowerindexpr, lowlist_item);
#endif
}
deparseExpr(lfirst(uplist_item), context);
appendStringInfoChar(buf, ']');
if (!first)
appendStringInfoString(buf, ", ");
deparseExpr(lfirst(lc), context);
first = false;
}

/* Enclose the ELT() expression */
appendStringInfoChar(buf, ')');

}

/*
Expand Down Expand Up @@ -1488,11 +1559,17 @@ foreign_expr_walker(Node *node, foreign_glob_cxt *glob_cxt,
* non-default collation.
*/
if (bms_is_member(var->varno, glob_cxt->relids) &&
var->varlevelsup == 0)
var->varlevelsup == 0 && var->varattno > 0)
{
/* Var belongs to foreign table */
/* Else check the collation */
collation = var->varcollid;
state = OidIsValid(collation) ? FDW_COLLATE_SAFE : FDW_COLLATE_NONE;

/* Mysql do not have Array data type */
if (type_is_array(var->vartype))
elog(ERROR, "mysql_fdw: Not support array data type\n");

}
else
{
Expand All @@ -1501,6 +1578,15 @@ foreign_expr_walker(Node *node, foreign_glob_cxt *glob_cxt,
var->varcollid != DEFAULT_COLLATION_OID)
return false;

/*
* System columns should not be sent to
* the remote, since we don't make any effort to ensure
* that local and remote values match (tableoid, in
* particular, almost certainly doesn't match).
*/
if (var->varattno < 0)
return false;

/* We can consider that it doesn't set collation */
collation = InvalidOid;
state = FDW_COLLATE_NONE;
Expand Down Expand Up @@ -1549,6 +1635,7 @@ foreign_expr_walker(Node *node, foreign_glob_cxt *glob_cxt,
{
SubscriptingRef *ar = (SubscriptingRef *) node;
#endif
Assert(list_length(ar->refupperindexpr) > 0);

/* Should not be in the join clauses of the Join-pushdown */
if (glob_cxt->is_remote_cond)
Expand All @@ -1558,25 +1645,55 @@ foreign_expr_walker(Node *node, foreign_glob_cxt *glob_cxt,
if (ar->refassgnexpr != NULL)
return false;

#if PG_VERSION_NUM >= 140000

/*
* Recurse into the remaining subexpressions. The container
* subscripts will not affect collation of the SubscriptingRef
* result, so do those first and reset inner_cxt afterwards.
*/
#else

/*
* Recurse to remaining subexpressions. Since the array
* subscripts must yield (noncollatable) integers, they won't
* affect the inner_cxt state.
*/
#endif
/* Allow 1-D subcription, other case does not push down */
if (list_length(ar->refupperindexpr) > 1)
return false;

if (!foreign_expr_walker((Node *) ar->refupperindexpr,
glob_cxt, &inner_cxt))
return false;
if (!foreign_expr_walker((Node *) ar->reflowerindexpr,
glob_cxt, &inner_cxt))

/* Disable slice by checking reflowerindexpr [:] */
if (ar->reflowerindexpr)
return false;

#if PG_VERSION_NUM >= 140000
inner_cxt.collation = InvalidOid;
inner_cxt.state = FDW_COLLATE_NONE;
#endif
/* Disble subcripting for Var, eg: c1[1] by checking T_Var */
if (!foreign_expr_walker((Node *) ar->refexpr,
glob_cxt, &inner_cxt))
return false;
#if PG_VERSION_NUM >= 140000

/*
* Container subscripting typically yields same collation as
* refexpr's, but in case it doesn't, use same logic as for
* function nodes.
*/
#else

/*
* Array subscripting should yield same collation as input,
* but for safety use same logic as for function nodes.
* Container subscripting should yield same collation as
* input, but for safety use same logic as for function nodes.
*/
#endif
collation = ar->refcollid;
if (collation == InvalidOid)
state = FDW_COLLATE_NONE;
Expand Down
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