Regex: Infinite recurssion when extracting columns from SQL

I am trying to get all the columns within a SQL query (including the sub selects). When the code hits matcher.find(). i get the following exception:

Exception in thread "main" java.lang.StackOverflowError
at java.util.regex.Pattern$Branch.match(Pattern.java: 4530)
at java.util.regex.Pattern$GroupHead.match(Pattern.ja va:4570)

I am not sure where in the regex is causing the inifinite recursion.
Can anyone shed light on this?

String regex = "^select(([^\$]|\\([^\\(]+\$)*)from";
Pattern pattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE | Pattern.DOTALL | Pattern.MULTILINE);
Matcher matcher = pattern.matcher(sql);
if (matcher.find()) {
// Get all groups for this match
for (int i = 0; i <= matcher.groupCount(); i++) {
String groupStr = matcher.group(i);
}
}

What does your sql variable look like?

I was googling for this problem, I came accross few posting where the string that i matching is large and if there is an alternation in the regex, it would cause stack over flow exception.

Here is the SQL i am using:

SELECT
P4.NAME REGION,
P3.NAME AREA,
P2.NAME AS MARKET,
P1.NAME AS CHANNEL,
SR.NO AS SR_NUMBER,
SR.NAME AS SR_NAME,
SR.ID SRID,
P.NO SITE_NUMBER,
P.NAME SITE_NAME,
P.ID SITEID,
S.NAME AS STATUS_NAME,
T.NAME AS TYPE_NAME,
AD.STREET AS ADDRESS,
AD.CITY_NAME AS CITY_NAME,
AD.STATE_NAME AS STATE_NAME,
AD.ZIP_CODE AS ZIP_CODE,
AD.LATITUDE_COORDINATE AS LATITUDE,
AD.LONGITUDE_COORDINATE AS LONGITUDE,
AD.COUNTRY_NAME AS COUNTRY_NAME,
AD.COUNTY AS COUNTY_NAME,
TEXT17 AS POINT_TO_POINT_TYPE,
A_STR.TEXT1 AS POINT_TO_POINT_DATA,
(select blah.id from blah where name = P4.NAME) Test,
TEXT18 AS FACILITY_TYPE,
BOOLEAN1 AS LAND_LEASED,
BOOLEAN2 AS TOWER_LEASED,
BOOLEAN3 AS BUILDING_LEASED,
BOOLEAN4 AS SPECTRUM_LEASED,
TEXT2 AS LEGACY_SITE_ID
FROM
GEMINI.PRP_PROPERTIES P,
GEMINI.PRP_PROPERTIES_EXT_STRING PES,
GEMINI.PRP_PROPERTIES_EXT_DATE PED,
GEMINI.PRP_PROPERTIES_EXT_BOOLEAN PEB,
GEMINI.PRP_PROPERTIES_EXT_NUMBER PEN,
GEMINI.PRP_PROPERTY_STATUSES S,
GEMINI.PRP_PROPERTY_TYPES T,
GEMINI.GEN_ADDRESSES AD,
GEMINI.PRP_PROPERTIES_ORG_UNITS SP,
GEMINI.HUR_ORGANIZATION_UNITS P1,
GEMINI.HUR_ORGANIZATION_UNITS P2,
GEMINI.HUR_ORGANIZATION_UNITS P3,
GEMINI.SCR_SEARCH_RINGS SR
WHERE A_STR.ID = P.ID
AND A_BOOL.ID = P.ID
AND S.ID = P.STATUS_ID
AND T.ID = P.TYPE_ID
AND AD.ID = P.PRIMARY_ADDRESS_ID
AND SR.ID = P.SEARCH_RING_ID
AND SP.PROPERTY_ID (+) = P.ID
AND P1.ID (+) = SP.ORGANIZATION_UNIT_ID
AND P2.ID (+) = P1.PARENT_ORGANIZATION_UNIT_ID
AND P3.ID (+) = P2.PARENT_ORGANIZATION_UNIT_ID
AND P4.ID (+) = P3.PARENT_ORGANIZATION_UNIT_ID
AND P.IS_DELETED = 0
AND P.DOMAIN_ID = <%DOMAIN_ID%>

Yeah, it's probably not an infinite recursion, but just a finite, very deep one - too deep for your stack size. Have you tried enlarging your stack?

Thanks for the reply, i am not sure IT guys will allow me to increase the stack size. The other bad thing is some times the sql i am parsing exceeds 2000 lines. Can you please let me know how to increase the stack size.

Thanks.

"ver sd",
Please check your private messages.
-Ben

Originally posted by ver sd:
Thanks for the reply, i am not sure IT guys will allow me to increase the stack size. The other bad thing is some times the sql i am parsing exceeds 2000 lines. Can you please let me know how to increase the stack size.

Thanks.

The stack is controlled by the "-Xss" switch on the command line. For example, to have a megabyte stack for each thread, add "-Xss1024k" to the command line.

Henry

I don't think increasing the stack size will help. You need to rewrite the regex so as to minimize the amount of backtracking it has to do. Try this one: