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implementing the hashbytes function in special function
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Signed-off-by: pranav jain <[email protected]>
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@pranavJ23
pranavJ23 committed Dec 19, 2024
1 parent 0b44cdc commit 126ade5
Showing 1 changed file with 39 additions and 47 deletions.
86 changes: 39 additions & 47 deletions contrib/babelfishpg_tsql/src/pltsql_coerce.c
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Original file line number Diff line number Diff line change
Expand Up @@ -416,6 +416,7 @@ tsql_special_function_t tsql_special_function_list[] =
{"sys", "stuff", "stuff", false, 4},
{"sys", "translate", "translate", false, 3},
{"sys", "trim", "Trim", false, 1},
{"sys", "hashbytes", "hashbytes", false, 2},
{"sys", "trim", "Trim", false, 2},
{"sys", "ltrim", "ltrim", false, 1},
{"sys", "rtrim", "rtrim", false, 1},
Expand Down Expand Up @@ -1123,41 +1124,6 @@ validate_special_function(char *func_nsname, char *func_name, int nargs, bool nu
return true;
}

/*
* Selects the best candidate function for HASHBYTES based on input types.
* Focuses on matching the second argument type, particularly for NVARCHAR.
* Returns a single best candidate from the sys schema, or NULL if none found.
*/
static FuncCandidateList
tsql_func_select_candidate_for_hashbytes(Oid *input_typeids, FuncCandidateList candidates)
{

FuncCandidateList current_candidate, best_candidate;
Oid sys_oid = get_namespace_oid("sys", false);
Oid *argtypes;
int nargs_func = 0;

/* Get the candidate with matching second argument type */
best_candidate = NULL;
for (current_candidate = candidates;
current_candidate != NULL;
current_candidate = current_candidate->next)
{
/* we should only consider candidates for hashbytes function from sys schema */
if (get_func_namespace(current_candidate->oid) != sys_oid)
return NULL;

get_func_signature(current_candidate->oid, &argtypes, &nargs_func);
if(input_typeids[1] == argtypes[1])
{
best_candidate = current_candidate;
}
}
if (best_candidate != NULL)
best_candidate->next = NULL;
return best_candidate;
}

/*
* tsql_func_select_candidate_for_special_func()
*
Expand All @@ -1168,23 +1134,20 @@ static FuncCandidateList
tsql_func_select_candidate_for_special_func(List *names, int nargs, Oid *input_typeids, FuncCandidateList candidates)
{
FuncCandidateList current_candidate, best_candidate;
Oid expr_result_type;
Oid expr_result_type, expr_arg_type;
char *proc_nsname;
char *proc_name;
bool is_func_validated;
int ncandidates;
Oid rettype;
Oid sys_oid = get_namespace_oid("sys", false);
Oid *new_input_typeids;
Oid *argtypes;
int nargs_func;
Oid second_arg_type;

DeconstructQualifiedName(names, &proc_nsname, &proc_name);

/* Specific handling for hashbytes function based on second input argument via tsql_func_select_candidate_for_hashbytes() */
if ((proc_nsname == NULL || strcmp(proc_nsname, "sys") == 0) && strcmp(proc_name, "hashbytes") == 0)
{
return tsql_func_select_candidate_for_hashbytes(input_typeids, candidates);
}

is_func_validated = validate_special_function(proc_nsname, proc_name, nargs, true);

/* Return NULL if function is not a special function */
Expand Down Expand Up @@ -1212,6 +1175,7 @@ tsql_func_select_candidate_for_special_func(List *names, int nargs, Oid *input_t

/* function based logic to decide return type */
expr_result_type = InvalidOid;
expr_arg_type = InvalidOid;
if (strlen(proc_name) == 4 && strncmp(proc_name,"trim", 4) == 0 && nargs == 2)
{
if ((*common_utility_plugin_ptr->is_tsql_nvarchar_datatype)(new_input_typeids[1])
Expand Down Expand Up @@ -1360,12 +1324,31 @@ tsql_func_select_candidate_for_special_func(List *names, int nargs, Oid *input_t
expr_result_type = get_sys_varcharoid();
}
}
else if (strlen(proc_name) == 9 && strncmp(proc_name,"hashbytes", 9) == 0 && nargs == 2)
{
if ((*common_utility_plugin_ptr->is_tsql_varchar_datatype)(new_input_typeids[1])
|| (*common_utility_plugin_ptr->is_tsql_bpchar_datatype)(new_input_typeids[1])
|| (*common_utility_plugin_ptr->is_tsql_text_datatype)(new_input_typeids[1])
|| new_input_typeids[1] == UNKNOWNOID)
{
expr_arg_type = get_sys_varcharoid();
}
else if((*common_utility_plugin_ptr->is_tsql_nvarchar_datatype)(new_input_typeids[1])
|| (*common_utility_plugin_ptr->is_tsql_nchar_datatype)(new_input_typeids[1]))
{
expr_arg_type = (*common_utility_plugin_ptr->lookup_tsql_datatype_oid) ("nvarchar");
}
else if(is_tsql_binary_family_datatype(new_input_typeids[1]))
{
expr_arg_type = (*common_utility_plugin_ptr->lookup_tsql_datatype_oid) ("bbf_varbinary");
}
}

/* free new_input_typeids, as they are no longer needed */
if (new_input_typeids)
pfree(new_input_typeids);

if (!OidIsValid(expr_result_type))
if (!OidIsValid(expr_result_type) && !OidIsValid(expr_arg_type))
return NULL;

/* Get the candidate with matching return type */
Expand All @@ -1380,13 +1363,16 @@ tsql_func_select_candidate_for_special_func(List *names, int nargs, Oid *input_t
continue;

rettype = get_func_rettype(current_candidate->oid);
get_func_signature(current_candidate->oid, &argtypes, &nargs_func);
second_arg_type = argtypes[1];

/* Ignore following definitions as these are used when no other potential definition can be used. */
if ((current_candidate->args[0] == TEXTOID && rettype == get_sys_varcharoid())
|| (current_candidate->args[0] == BYTEAOID && rettype == BYTEAOID))
continue;

if (expr_result_type == rettype)
if ((OidIsValid(expr_result_type) && expr_result_type == rettype)
|| (OidIsValid(expr_arg_type) && expr_arg_type == second_arg_type))
{
best_candidate = current_candidate;
ncandidates++;
Expand All @@ -1401,9 +1387,15 @@ tsql_func_select_candidate_for_special_func(List *names, int nargs, Oid *input_t
/* multiple suitable candidates with same return type should not exist in sys schema. */
else if (ncandidates > 1)
{
ereport(ERROR,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("multiple definitions of function %s.%s with return type %s found.", proc_nsname, proc_name, format_type_be(expr_result_type))));
if(OidIsValid(expr_result_type))
ereport(ERROR,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("multiple definitions of function %s.%s with return type %s found.", proc_nsname, proc_name, format_type_be(expr_result_type))));

else if(OidIsValid(expr_arg_type))
ereport(ERROR,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("multiple definitions of function %s.%s with second arg type %s found.", proc_nsname, proc_name, format_type_be(expr_arg_type))));
}

if (best_candidate != NULL)
Expand Down

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