REGEXP_ compare two tokenized strings

Question

Hi,
I need to compare two fields (from two tables), to see if any of the tokenized contents match.
I have two tables with a "name" field, but the names might be incomplete or in random order. To get a match, I just need 1 part of both to really match, for example "John Doe" should match to "Doe J.".
Something like:
SELECT names1.name, names2.name
FROM names1, names2
WHERE INSTR(names1.name, REGEXP_SUBSTR(names2.name, '[[:alpha:]]+')) > 0
But the statement should consider all tokens, not just the first one as in the example.
Any suggestion on how to achieve this?
Thanks,
K.

Answer 1

The performance of the regexp_instr in the where clause is terrible ... I stopped working out other scenarios, because the conclusion will be the same:
SQL> create table names1
  2  as
  3  select 1 id, 'John Doe' name from dual union all
  4  select 2, 'Larry Ellison' from dual union all
  5  select 3, 'Catharina-Amalia Beatrix Carmen Victoria van Oranje' from dual union all
  6  select object_id, o
  7    from ( select object_id
  8                , owner || object_name o
  9                , ntile(200) over (order by object_id) nt
10             from all_objects
11         )
12   where nt = 11
13  /
Tabel is aangemaakt.
SQL> create table names2
  2  as
  3  select 1001 id, 'Doe J.' name from dual union all
  4  select 1002, 'Gates Bill' from dual union all
  5  select 1003, 'Beatrix Wilhelmina Armgard van Oranje' from dual union all
  6  select object_id, o
  7    from ( select object_id
  8                , owner || object_name o
  9                , ntile(200) over (order by object_id) nt
10             from all_objects
11         )
12   where nt = 22
13  /
Tabel is aangemaakt.
SQL> select count(*) from names1
  2  /
  COUNT(*)
       241
1 rij is geselecteerd.
SQL> select count(*) from names2
  2  /
  COUNT(*)
       241
1 rij is geselecteerd.
SQL> exec dbms_stats.gather_table_stats(user,'names1')
PL/SQL-procedure is geslaagd.
SQL> exec dbms_stats.gather_table_stats(user,'names2')
PL/SQL-procedure is geslaagd.
SQL> set timing on
SQL> set autotrace on
SQL> select distinct n1.original_name name1
  2       , n2.original_name name2
  3    from ( select id
  4                , name
  5                , original_name
  6             from names1
  7            model
  8                  return updated rows
  9                  partition by (id)
10                  dimension by (0 i)
11                  measures (' ' || name || ' ' name, cast(null as varchar2(100)) original_name)
12                  rules iterate (100) until (iteration_number = length(regexp_replace(name[0],'[^ ]')) - 2)
13                  ( name[iteration_number+1] = regexp_substr(name[0],'[^ ]+',1,iteration_number+1)
14                  , original_name[iteration_number+1] = trim(name[0])
15                  )
16         ) n1
17       , ( select id
18                , name
19                , original_name
20             from names2
21            model
22                  return updated rows
23                  partition by (id)
24                  dimension by (0 i)
25                  measures (' ' || name || ' ' name, cast(null as varchar2(100)) original_name)
26                  rules iterate (100) until (iteration_number = length(regexp_replace(name[0],'[^ ]')) - 2)
27                  ( name[iteration_number+1] = regexp_substr(name[0],'[^ ]+',1,iteration_number+1)
28                  , original_name[iteration_number+1] = trim(name[0])
29                  )
30         ) n2
31   where n1.name = n2.name
32  /
NAME1
NAME2
Catharina-Amalia Beatrix Carmen Victoria van Oranje
Beatrix Wilhelmina Armgard van Oranje
John Doe
Doe J.
2 rijen zijn geselecteerd.
Verstreken: 00:00:00.07
Uitvoeringspan
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=8 Card=581 Bytes=987
          70)
   1    0   SORT (UNIQUE) (Cost=8 Card=581 Bytes=98770)
   2    1     HASH JOIN (Cost=7 Card=581 Bytes=98770)
   3    2       VIEW (Cost=3 Card=241 Bytes=20485)
   4    3         BUFFER (SORT)
   5    4           SQL MODEL (ORDERED FAST)
   6    5             TABLE ACCESS (FULL) OF 'NAMES1' (TABLE) (Cost=3
          Card=241 Bytes=5784)
   7    2       VIEW (Cost=3 Card=241 Bytes=20485)
   8    7         BUFFER (SORT)
   9    8           SQL MODEL (ORDERED FAST)
  10    9             TABLE ACCESS (FULL) OF 'NAMES2' (TABLE) (Cost=3
          Card=241 Bytes=5784)
Statistics
        387  recursive calls
          0  db block gets
         52  consistent gets
          0  physical reads
          0  redo size
        590  bytes sent via SQL*Net to client
        508  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
         11  sorts (memory)
          0  sorts (disk)
          2  rows processed
SQL> select n1.name name1
  2       , n2.name name2
  3    from names1 n1
  4       , names2 n2
  5   where regexp_instr  ( ' ' || n1.name || ' ',       ' ' || replace( n2.name, ' ', ' | ' ) || ' '  ) > 0
  6  /
NAME1                                                        NAME2
John Doe                                                     Doe J.
Catharina-Amalia Beatrix Carmen Victoria van Oranje          Beatrix Wilhelmina Armgard van Oranje
2 rijen zijn geselecteerd.
Verstreken: 00:00:46.54
Uitvoeringspan
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=218 Card=2904 Bytes=
          121968)
   1    0   NESTED LOOPS (Cost=218 Card=2904 Bytes=121968)
   2    1     TABLE ACCESS (FULL) OF 'NAMES1' (TABLE) (Cost=3 Card=241
           Bytes=5061)
   3    1     TABLE ACCESS (FULL) OF 'NAMES2' (TABLE) (Cost=1 Card=12
          Bytes=252)
Statistics
          1  recursive calls
          0  db block gets
        728  consistent gets
          0  physical reads
          0  redo size
        590  bytes sent via SQL*Net to client
        508  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          2  rows processedRegards,
Rob.