MonetDB: Jul2021 - exp_relname is recursive, so check the stack ...

[Pedro Ferreira]

Changeset: 9dce0c3e63cd for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB/rev/9dce0c3e63cd
Modified Files:
        sql/server/rel_optimizer.c
Branch: Jul2021
Log Message:

exp_relname is recursive, so check the stack beforehand. Also don't attempt to 
destroy the selection over the merge table multiple times


diffs (44 lines):

diff --git a/sql/server/rel_optimizer.c b/sql/server/rel_optimizer.c
--- a/sql/server/rel_optimizer.c
+++ b/sql/server/rel_optimizer.c
@@ -8906,14 +8906,14 @@ typedef struct {
 static sql_rel *
 merge_table_prune_and_unionize(visitor *v, sql_rel *mt_rel, 
merge_table_prune_info *info)
 {
+       if (mvc_highwater(v->sql))
+               return sql_error(v->sql, 10, SQLSTATE(42000) "Query too 
complex: running out of stack space");
+
        sql_rel *nrel = NULL;
        sql_table *mt = (sql_table*) mt_rel->l;
        const char *mtalias = exp_relname(mt_rel->exps->h->data);
        list *tables = sa_list(v->sql->sa);
 
-       if (mvc_highwater(v->sql))
-               return sql_error(v->sql, 10, SQLSTATE(42000) "Query too 
complex: running out of stack space");
-
        for (node *nt = mt->members->h; nt; nt = nt->next) {
                sql_part *pd = nt->data;
                sql_table *pt = find_sql_table_id(v->sql->session->tr, mt->s, 
pd->member);
@@ -9223,10 +9223,7 @@ merge_table_prune_and_unionize(visitor *
                        }
                }
        }
-       if (info)
-               rel_destroy(info->sel); /* mt_rel must be under info->sel */
-       else
-               rel_destroy(mt_rel);
+       rel_destroy(mt_rel);
        return nrel;
 }
 
@@ -9308,6 +9305,10 @@ rel_merge_table_rewrite(visitor *v, sql_
                        }
                        if (!(rel = merge_table_prune_and_unionize(v, bt, 
info)))
                                return NULL;
+                       if (sel) {
+                               sel->l = NULL; /* The mt relation has already 
been destroyed */
+                               rel_destroy(sel);
+                       }
                        v->changes++;
                }
        }
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