A database structure that can improve the speed of queries at the cost of disk space and slower inserts/updates. It stores a copy of one or more columns but structures the data differently to allow for faster access.
0
votes
1answer
33 views
Will Partitions and Indexes on the same table help in performace of Inserts and Selects?
I have a table containing the list of visitors and this table has the following information.
Visitor Browser Information
Visitor Location Information
Visitor Time Information
No of Visits
I have a ...
3
votes
2answers
19 views
How to design indexes for columns with NULL values in MySQL?
I have a database with 40 million entries and want to run queries with the following WHERE clause
...
WHERE
`POP1` IS NOT NULL
&& `VT`='ABC'
&& (`SOURCE`='HOME')
&& ...
0
votes
0answers
26 views
Longest prefix search in Oracle
I have a list of phone number prefixes defined for large number of zones (in query defined by gvcode and cgi).
I need to efficiently find a longest prefix that matches given number PHONE_NR.
I use ...
5
votes
2answers
108 views
Does an index with multiple columns make a similar index redundant?
Let's say I have a table that looks like this:
CREATE TABLE Activity (
ActivityID int primary key identity(1,1) ,
ActivityName nvarchar(10),
InactiveFlag bit
)
with an index that looks ...
-2
votes
0answers
45 views
Unexpected index scan against partitioned table [closed]
I have a set of partitioned tables with CIX on (ID, DATE) and partitioned on DATE.
There is another identical set of non-partitioned tables with CIX on ID.
Case A: T1 and T2 are non-partitioned ...
3
votes
0answers
27 views
custom population of full text index
Is there any way to populate a full text search index without storing the backing information in the database?
I don't mean using remote-blob-storage or FILESTREAM types. The backing information is a ...
6
votes
1answer
74 views
Dropping Hypothetical Indexes
In the past I thought I'd deleted hypothetical indexes using either a DROP INDEX statement for clustered indexes and DROP STATISTICS statement for non-clustered indexes.
I have a database that is ...
4
votes
2answers
73 views
Should I use a composite or single-column index?
I have the following columns in my database table (Medicines).
ID bigint,
MedicineName nvarchar(50),
BrandName nvarchar(50),
MedicineCode nvarchar(20),
and price,quantity.
I am making a stored ...
7
votes
4answers
408 views
Index Seek vs Index Scan
Looking at an execution plan of a slow running query and I noticed that some of the nodes are index seek and some of them are index scan.
What is the difference between and index seek and an index ...
0
votes
0answers
32 views
How to make continues cluster?
I have a report table with the following index:
providerid, date
The table is around 30M records and it grows about 100K rows per day.
I want to use in the index above as a cluster, but as I ...
-3
votes
0answers
28 views
How do I add a index column to a database with non unique columns [closed]
I have a database with non unique data in columns, How do I add a index column or add a primairy key column?
0
votes
1answer
52 views
Can I use the database and query it while full-text indexing?
I need to index my database, but I need to query it while it is indexing, it may take a long time, can I do that?
1
vote
2answers
87 views
SQL Server clustered index high fragmentation
I've got a Table with an Integer (4bytes) as primary key. it's defined as an identity. it is also the clustered index.
Inserts are working perfectly fine. After inserting 2000 rows the fragmentation ...
0
votes
1answer
51 views
Two identical MySQL tables, one not using indexes
I have one MySQL Server (5.0.37) on a Linux Server that have many databases. Some of them (12) have each an identical table to log sensors data.
Schema of one table
CREATE TABLE `measuresHistory` (
...
0
votes
0answers
8 views
Fine grained (milliseconds) temporal indexes in neo4j
What are the best practices for modeling fine grained timelines in neo4j? If I were to use milliseconds as the grain in the pattern described here and here would it prove somehow problematic and ...
6
votes
1answer
183 views
MySQL Hanging Completely when `ALTER TABLE… ENABLE KEYS`
I know very little about database administration but I have to deal with some very large tables on my site.
This server has 64GB of RAM and Intel Core i7-3820 (4 x 3600 MHz). Most of everything it ...
3
votes
1answer
57 views
How can I get this query to use it's index?
Queries matching this query below shows up in the slow log (with different contentVersionId & modifiedDateTime).
As I don't really know what I'm doing I tried adding indexes to all columns in ...
5
votes
2answers
158 views
Why disabling a clustered index makes the table inaccessible?
When an index is disabled, the definition remains in the system catalog but is no longer
used.
SQL Server does not maintain the index (as data in the table changes), and the index
cannot be used to ...
0
votes
1answer
39 views
Index on a query with order
I have the following table with >1M rows:
CREATE TABLE `wishlist_place` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`wishlist_id` int(11) DEFAULT NULL,
`place_id` int(11) DEFAULT NULL,
`city_id` ...
1
vote
1answer
59 views
Varchar index - will hashing value make it faster?
I have a VARCHAR(1000) column in a table. It will contain strings that will not be guaranteed to be unique. I have a query that searches this column as part of a WHERE IN clause, the list of values in ...
1
vote
2answers
116 views
Auto-generate scripts to create tables, indexes, etc
In SSMS, we can right click a database/table/index/... and select the "Script As" option to generate a drop and create script.
Is there a way to automate this script generation and drop the scripts ...
0
votes
2answers
91 views
Sync Indexes between two tables
I need to automate and Sync only indexes between two tables ( Primary and Stage_Table) within the same database.
I tried using SSIS SQL Server Objects Task, but looks like it works only when we sync ...
4
votes
1answer
136 views
Indexes file damaged, was on ramdisk
I have put some of my indexes into a filegroup that contains one file, that file is on the ramdisk, the performance is great, but the problem is that the file was deleted incorrectly (the file ...
2
votes
0answers
95 views
Why does CREATE INDEX … WITH ONLINE=ON block access to the table over a period of minutes?
I have an existing table:
CREATE TABLE dbo.ProofDetails
(
ProofDetailsID int NOT NULL
CONSTRAINT PK_ProofDetails
PRIMARY KEY CLUSTERED IDENTITY(1,1),
ProofID int NULL,
...
2
votes
1answer
41 views
Rebuilding Unique Index with uniqueidentifier in SQL Azure never succeeds
We have a number of tables (~1M records) that have a column on them defined as: [GlobalID] [uniqueidentifier] NOT NULL that gets auto-populated with newid(). We use this ID for synchronizing data ...
0
votes
0answers
22 views
MySQL (v5.6.11) InnoDB 5.6.11 restoring indexes during table copy
When i see the profile for my optimize table query here is what i see for the InnoDB storage engine 5.6.11:
+----------------------+------------+
| Status | Duration |
...
0
votes
2answers
108 views
How do you correct a corrupted index in Oracle?
I have this ORA error in our logs:
Caused by: java.sql.BatchUpdateException: ORA-01578: ORACLE data block corrupted (file # 8, block # 22921) ORA-01110: data file 8: ...
0
votes
1answer
58 views
How do you correct a corrupted index in Oracle? [duplicate]
I have this ORA error in our logs:
Caused by: java.sql.BatchUpdateException: ORA-01578: ORACLE data block corrupted (file # 8, block # 22921)
ORA-01110: data file 8: ...
0
votes
0answers
45 views
one vs two column index difference when doing JOIN query?
Let`s suppose that alfa,beta and gamma contains milions of rows so we need to create indexes obviously to get optimal performace for this query :
SELECT * FROM alfa
JOIN beta on beta.id = ...
1
vote
2answers
30 views
Why PostreSQL 9.2 does not use index scan if it can?
My PosgreSQL planner (9.2) does not pick index and rather choose to do seq scan.
Here is my table. The index I am talking about is name_left_prefix
cwu=# \d web_city;
...
0
votes
2answers
46 views
Is there slowdown inserting into an InnoDB table that has no index set?
I have an old application with lots of InnoDB tables, that have no indexes at all, not even a primary ID or such.
Those tables only contain a few thousand rows.
Would it be faster to INSERT data ...
1
vote
0answers
29 views
parenthetic grouping of join clauses
What is the difference between these joins?
a left join b left join c
(a left join b) left join c
a left join (b left join c)
Does the grouping only affect the order of the joins? Will the query ...
1
vote
2answers
122 views
Clustered vs Nonclustered Index
My database currently has a primary Key/Clustered index on the ID column for each table. However, the application that connects to the database is always looking at views defined as:
SELECT * FROM ...
2
votes
1answer
73 views
mysql: need help to optimize my query/table
I'm wondering if someone could help me optimize my tables/query to speed up a query. It is currently running ridiculously slow. I think a well-thought out index could help me. Any help would be really ...
3
votes
2answers
89 views
Reducing Log Impact During Re-Indexing
We use Ola's maintenance solution and its great.
Regardless of method for re-indexing a major friction point with IT is the amount of log generated during the weekly re-indexing process. For a 1TB ...
2
votes
1answer
62 views
Validate Primary Key and Index Selection
I have a table that will store transaction data from store sales registers, I have read quite a bit on index and key choice and below is what I have concluded is the best option but I am new to this ...
3
votes
1answer
77 views
In MySQL, does the order of the columns in a WHERE clause affect query performance,why?
I have a query that doesn't use any indexes:
SELECT 32,
guid,
1,
1,
1,
0,
5
FROM test
WHERE level >= 20
AND ( ( fun_GetIndexValue(data, 354) ...
2
votes
1answer
39 views
Do I need to reenter old data after adding an index to a table?
I want to add index to my tables. Some of my tables already have couple thousand rows.
Do I need to reenter my stored data after adding index to columns (to make them aware of index/so the indexing ...
2
votes
2answers
88 views
Suspended in index rebuild
In SQL Server 2012, an Index Rebuild job is taking a very long time (up to 8 hours). However, not even one Index rebuild completed, so I stopped the index job.
In monitoring SQL task:
state = ...
5
votes
1answer
66 views
When REBUILDing indexes on SQL Server, what bearing does tempdb & LOG disk speed have?
Say I have the a data disk that is 50x faster than the LOG and tempdb (measured by Random Write speed) disk. (Don't ask why that's something we'll be fixing if needed)
I have a table that's got 19 ...
0
votes
0answers
32 views
The best approach to index dynamic query in MongoDB
I am working on log managment system where user will be able to upload logs from file. I have 'event' collection where I store all events from all sources (each source can have different log format ...
1
vote
1answer
66 views
SQL Index order and performance based on cardinality and data
I've been working quite a bit on a query that's not operating very efficiently on a DB2 database. The thing will return up to 30k rows or so and take up to 10 seconds. I've been working on getting ...
3
votes
3answers
155 views
Optimizing queries on a range of timestamps (two columns)
I use postgresql-9.1 with ubuntu 12.04.
I need to select records inside a range of time: my table time_limits has two timestamp fields and one property integer. Indeed there are other info columns ...
4
votes
3answers
331 views
Should I seperate frequently updated columns
I have a users table that contains users' information and a column named credits that is frequently updated.
On index page I'm showing list of users with basic user information but I don't need ...
3
votes
1answer
76 views
How can I alter the fill factor of an index outside of an ALTER INDEX command?
I am using a COTS package to perform index rebuilds across my SQL Server portfolio. The package unfortunately doesn't have an option to set index fill factors globally for an individual instance or DB ...
4
votes
2answers
136 views
Inner join using an array column
Having trouble indexing and executing a query in O (log n) time.
The query includes an INNER JOIN, an ORDER BY, and an equality operation. If I understand the laws of databases correctly, a query can ...
2
votes
1answer
145 views
Bitmask Flags with Lookup Tables Clarification
I've received a dataset from an outside source which contains several bitmask fields as varchars. They come in length as low as 3 and as long as 21 values long. I need to be able to run SELECT queries ...
1
vote
1answer
18 views
Big jump in search time for Postgres Index query for results with high selectivity
I am doing some performance comparison of databases and lucene for full-text searching.
So I use Postgres to create an Index for the data to search:
CREATE INDEX bodies_index
ON bodies
USING gin
...
3
votes
1answer
105 views
Why is a hash match operator in this very basic query
I'm beginning to learn some about looking at execution plans and making queries more efficient
Consider these two basic queries
select distinct pat_id, drug_class, drug_name from rx
select pat_id, ...
5
votes
2answers
258 views
Recreate Indexes on 1 billion record table
I have a table with over 1 billion records and it has 6 indexes (including Clustered index (ID)). I need to partition this table on a new Clustered index with date column. I have just enough space ...
