I have a numeric string column in oracle with or without leading zeros samples:
00000000056
5755
0123938784579343
00000000333
984454
The issue is that partial Search operations using like are very slow
select account_number from accounts where account_number like %57%
one solution is to restrict the search to exact match only and add an additional integer column that will represent the numeric value for exact matches.
At this point I am not sure we can add an additional column,
Do you guys have any other ideas?
Is it possible to tell Oracle to index the numeric string column as an integer value so we can do exact numeric match on it?
for example query on value :00000000333
will be:
select account_number from accounts where account_number = '333'
While ignoring the leading zeros.
I can use regex_like and ignore them, but I am afraid its going to be slow.
Oracle supports function based indexes. SO if you index the result of to_number:
CREATE INDEX acocunt_number_idx
ON accounts(TO_NUMBER(account_number))
The way, if you use a query with to_number for the exact numeric value, the index will be used:
SELECT account_number
FROM accounts
WHERE TO_NUMBER(account_number) = 333
You can use to_number.
select account_number from accounts
where to_number(account_number) = 333
Related
I am using regexp_like function to search specific patterns on a column. But, I see this query is not taking the index created on this column instead going for full table scan. Is there any option to create function based index for regexp_like so that my query will use that index? Here, the pattern SV4889 is not constant expression but it will vary every time.
select * from test where regexp_like(id,'SV4889')
Yup. Regular expressions do not use indexes. What can you do?
Well, if you are just looking for equality, then use equality:
where id = 'SV4889'
This will use an index on (id).
If you are looking for a leading value, then use like:
where id like 'SV4889%'
This will use an index because the wildcard is at the end of the pattern.
If you are storing multiple values in the column, say 'SV4889,SV4890' then fix your data model. It is broken! You should have another table with one row per id.
Finally, if you really need more sophisticated full text capabilities, then look into Oracle's support for full text indexes. However, such capabilities are usually not needed on a column called id.
You can add a virtual column to your table to determine if the substring you're interested in exists in the field, then index the virtual column. For example:
ALTER TABLE TEST
ADD SV4889_FLAG CHAR(1)
GENERATED ALWAYS AS (CASE
WHEN REGEXP_LIKE(ID,'SV4889') THEN 'Y'
ELSE 'N'
END) VIRTUAL;
This adds a field named SV4889_FLAG to your table which will contain Y if the text SV4889 exists in the ID field, and N if it doesn't. Then you can create an index on the new field:
CREATE INDEX IDX_TEST_SV4889_FLAG
ON TEST (SV4889_FLAG);
So to determine if a row has 'SV4889' in it you can use a query such as:
SELECT *
FROM TEST
WHERE SV4889_FLAG = 'Y'
db<>fiddle here
i have subquery, that returns me varchar column, in some cases this column contains only numeric values and in this cases i need to cast this column to bigint, i`ve trying to use CAST(case...) construction, but CASE is an expression that returns a single result and regardless of the path it always needs to result in the same data type (or implicitly convertible to the same data type). Is there any tricky way to change column datatype depending on condition in PostgreSQL or not? google cant help me((
SELECT
prefix,
module,
postfix,
id,
created_date
FROM
(SELECT
s."prefix",
coalesce(m."replica", to_char(CAST((m."id_type" * 10 ^ 12) AS bigint) + m."id", 'FM0000000000000000')) "module",
s."postfix",
s."id",
s."created_date"
FROM some_subquery
There is really no way to do what you want.
A SQL query returns a fixed set of columns, with the names and types being fixed. So, a priori what you want to do does not fit well within SQL.
You could work around this, by inventing your own type, that is either a big integer or a string. You could store the value as JSON. But those are work-arounds. The SQL query itself is really returning one "type" for each column; that is how SQL works.
I would like to ask if it is possible to do this:
For example the search string is '009' -> (consider the digits as string)
is it possible to have a query that will return any occurrences of this on the database not considering the order.
for this example it will return
'009'
'090'
'900'
given these exists on the database. thanks!!!!
Use the Like operator.
For Example :-
SELECT Marks FROM Report WHERE Marks LIKE '%009%' OR '%090%' OR '%900%'
Split the string into individual characters, select all rows containing the first character and put them in a temporary table, then select all rows from the temporary table that contain the second character and put these in a temporary table, then select all rows from that temporary table that contain the third character.
Of course, there are probably many ways to optimize this, but I see no reason why it would not be possible to make a query like that work.
It can not be achieved in a straight forward way as there is no sort() function for a particular value like there is lower(), upper() functions.
But there is some workarounds like -
Suppose you are running query for COL A, maintain another column SORTED_A where from application level you keep the sorted value of COL A
Then when you execute query - sort the searchToken and run select query with matching sorted searchToken with the SORTED_A column
I have a table which contains a column having alphanumeric values which is stored as a string. I have multiple values in that column having values such as F4737, 00Y778, PP0098, XXYYYZ etc.
I want to extract values starting with a series of F and must have numeric values in that row.
Alphanumeric column is the unique column having unique values but the rest of the columns contain duplicate values in my table.
Futhermore, once these values are extracted I would like to pick up the max value from the duplicate row,for eg:
Suppose I have F4737 and F4700 as a unique Alphanumeric row, then F4737 must be extracted from it.
I have written a query like this but the numeric values are not getting extracted from this query:
select max(Alplanumeric)
from Customers
where Alplanumeric '%[F0-9]%
or
select max(Alplanumeric)
from Customers
where Alplanumeric like '%[0-9]%'
and Alplanumeric like 'F%'**
I run the above query but I am only getting the F series if I remove the numeric part from the above query. How do I extract both, the F starting series as well as the numeric values included in that row?
Going out on a limb, you might be looking for a query like this:
SELECT *, substring(alphanumeric, '^F(\d+)')::int AS nr
FROM customers
WHERE alphanumeric ~ '^F\d+'
ORDER BY nr DESC NULLS LAST
, alphanumeric
LIMIT 1;
The WHERE conditions is a regular expression match, the expression is anchored to the start, so it can use an index. Ideally:
CREATE INDEX customers_alphanumeric_pattern_ops_idx ON customers
(alphanumeric text_pattern_ops);
This returns the one row with the highest (extracted) numeric value in alphanumeric among rows starting with 'F' followed by one ore more digits.
About the index:
PostgreSQL LIKE query performance variations
About pattern matching:
Pattern matching with LIKE, SIMILAR TO or regular expressions in PostgreSQL
Ideally, you should store the leading text and the following numeric value in separate columns to make this more efficient. You don't necessarily need more tables like has been suggested.
I found this odd behavior and I'm breaking my brains with this... anyone has any ideas?
Oracle 10g:
I have two different tables, both have this column named "TESTCOL" as Varchar2(10), not nullable.
If I perform this query on table1, i get the proper results:
select * from table1 where TESTCOL = 1234;
Note that I'm specifically not placing '1234'... it's not a typo, that's a dynamic generated query and I will try not to change it (at least not in the near future).
But, if I run the same query, on table2, I get this error message:
ORA-01722: Invalid number
Both queries are run on the same session, same database.
I've been joining these two tables by that column and the join works ok, the only problem shows whenever I try to use that condition.
Any ideas on what could be different from one table to the other?
Thanks in advance.
If TESTCOL contains non-numbers, then Oracle might run into problems when converting TESTCOL entries to numbers. Because, what it does internally, is this:
select * from table1 where TO_NUMBER(TESTCOL) = 1234;
If you're so sure that 1234 cannot be expressed as a VARCHAR literal, then try this instead, in order to compare varchar values, rather than numeric ones:
select * from table1 where TESTCOL = TO_CHAR(1234);
Well obvious TABLE2.TESTCOL contains values which are not numbers. Comparing a string to a numeric literal generates an implicit conversion. So any value in TESTCOL hich cannot be cast to a number will hurl ORA-1722.
It doesn't hit you where you compare the two tables because you are comparing strings.
So you have a couple of options, neiher of which you will like. The most obvious answer is to clean the data so TABLE2 hdoesn't contain non-numerics. Ideally you should combine this with changing the column to a numeric data type. Otherwise you can alter the generator so it produces code you can run against a shonky data model. In this case that means wrapping literals in quote marks if the mapped column has a character data type.
You are hitting the perils of implicit typecasting here.
With the expression testcol = 1234 you state that you want to treat testcol as a numeric column, so Oracle tries to convert all values in that column to a number.
The ORA-01722 occurs because apparently at least one value in that column is not a number.
Even though you claim that this is "not a typo" it indeed is one. It's a syntactical error.
You will have to declare your parameter as a string literal using single quotes: where testcol = '1234'
Creating a correct condition is the only solution to your problem.
The following should work. Just replace the "your where".
select *
from table1
where (select TO_NUMBER(TESTCOL)
from table2
where "your where") = 1234;