My idea is to create a website for storing big amount of information, and I would like to know how many records can we store in an Apex table?
Apex is a tool, it doesn't store anything. It is the database that does so.
If that database is Oracle, you most probably shouldn't worry as sky is the limit. OK, not really - disk space is.
For more info:
19c physical database limits
19c logical database limits
(as 19c is the current release)
You don't specify the version of the database. ALWAYS specify version when asking these types of questions.
You don't specify logical or physical maximum. Physical is limited by disk space. Per the docs, logical is unlimited.
Related
We're running Oracle 12c SE. I've read a lot of postings that say v$segment_statistics may have information on which are the most frequently queried or updated objects. However, can that be broken down? Say that one might want to see during what times of the day certain objects are hotter than other objects, or perhaps number of physical reads or writes per hour for a given table?
Does Oracle SE offer this an any of the v$ views?
It sounds like you are describing dba_hist_seg_stat which is one of the tables that is populated as part of the Automatic Workload Repository (AWR). If you're on the standard edition, I don't believe querying these views would violate your license agreement but I don't keep up to date with changes to licensing terms particularly for the standard edition.
You could replicate this functionality yourself by putting together a job that runs every few minutes, queries v$segment_statistics, and writes the delta from the prior snap to a custom table. You could then query that table to see what activity was going on at different points in time.
Is there a way for me to test a new index (i.e. in memory?) without actually creating it yet? I would like to test it out and see if the Explain Plan is better before I hand off the index creation to the DBA.
My database is Oracle 12c.
Starting with 11g Oracle prepared exact for this reason inivisible indexes - the basic idea is simple.
You created a new indes as inivisible. i.e. no other session will see it and will not get possible negative sideffects (note that contrary to a popular belief more indixes means better performance - a new index can ruin the performence of some queries).
So only session that sets OPTIMIZER_USE_INVISIBLE_INDEXES can use and test the invisible index. Only after you are sure there are no negative effect, you can ALTER the index as visible.
See here for more details
Plain answer: NO. Invisible indexes still need to be created on storage Location - not Memory,
Create a subset of your data in the same way it is stored - i.e. same tablespace, storage Location etc. to reduce time for creating it. Unfortunatly this is not a 100% solution. Ask your DBA if there are times where DB not used heavily and create the index during that slot.
I'm adjusting my oracle table definition for cockroachdb, is there any equivalent to oracle SEGMENT CREATION in cockroachdb?
I also asked this question on cockroachDB forum.
CockroachDB does not have anything exactly equivalent to Oracle's "segments". It has "ranges", which serve some of the same purposes but do not represent a pre-allocation of space. There are no options at table creation time that control the creation of ranges. (You can change range_max_bytes in a zone config, although that's not the same as the Oracle option that I think you're referring to). See the FAQ for more on ranges.
I have created emp table to store employees information and their PP size photo.
this table has empno (number), emp_image_link(varchar2), .... etc fields.
empno is auto generated using a database trigger (max empno+1).
Image : I don't want to store images into the database since I believe it will cause problems in terms of size, performance and portability. So images should be in the file system at D:\images\
and images URL should be D:\images\empno.jpg, which means emp_image_link field will contain only the image link.
I have searched Google a lot about this, everyone is discussing about how to store into the database.
I did not find any information about how to store only the link instead of the image.
I am going to use Oracle Forms Developer 11gR2.
Can anyone give me an idea of how I can do that please.
Thank you in advance.
Murshed Khan
"i dont want to store images into the database since it will cause
problem in terms of size, performance and portability i believe. so
images should be in the file system"
Your points are not valid ones.
Size. Passport photos are pretty small, so unless you are storing pictures with extremely high pixel counts they won't take up a lot of disk. Either way they will consume comparable amounts of space in the database and on the OS.
Performance. The only possible concern would be the network traffic between the database server and the middle-tier server. This would be a function of size, so may or may not be a real issue. Using na OS file store would introduce a time delay while you retrieve the JPG for each record.
Portability. An all-in-the-database solution is more portable than what you're proposing. Nothing breaks like directory paths.
One thing you haven't considered but you really should is DML on the employee records. If the pictures are stored in the database they are committed in the same transaction as (hence consistent with) the rest of the data, they are backed-up at the same time and they are recoverable in the same window. None of which applies to an OS directory on a separate server.
"Storing in the file system ... I got the solution using BFILE "
BFILE is the mechanism for linking a database record with an OS file. So it is the appropriate solution for the problem as you define it. But the BFILE points to files on the database server, so you would lose the only possibly efficiency to be gained from not storing records in the database, the network traffic between the database and middle tier servers. BFILEs would not be backed up with the database or subject to any transactional consistency.
"empno is auto generated using a database trigger (max empno+1)"
Another bad idea. It doesn't scale and more importantly it doesn't work in a multi-user environment. Please use a sequence, they're designed for this task.
Initiation
I have a SQL Server Express 2008 R2 running. There are ten users who read / write permanently to the same tables using Stored Procedures. They do this day and night.
Problem
The performance of the Stored Procedures is getting lower and lower with increasing database size.
A Stored Procedure call needs avg 10ms when the database size is about 200MB.
The same call needs avg 200ms when the database size is about 3GB.
So we have to cleanup the database once a month.
We already did index optimization for some tables with positive effects but the problem still exists.
Finally im not a SQL Server expert. Could you give me some hints to start getting rid of this performance problem?
Download and read Waits and Queues
Download and follow the Troubleshooting SQL Server 2005/2008 Performance and Scalability Flowchart
Read Troubleshooting Performance Problems in SQL Server 2005
The SQL Server Express Edition limitations (1GB memory buffer pool, only one socket CPU used, 10GB database size) are unlikely to be the issue. Application design, bad queries, excessive locking concurrency and poor indexing are more likely to be the problem. The linked articles (specially the first one) include methodology on how to identify the bottleneck(s).
This is MOST likely simple a programmer mistake - sounds like you simply do either have:
Non proper indexing on some tables. THis is NOT optimization - bad indices is like broken HTML for web people, if you have no index then basically you are not using SQL as it is supposed to be used, you should always have proper indexes.
Not enough hardware, such as RAM. yes, it can manage a 10gb database, but if your hot set (the suff accessed all the time) is 2gb and you have only 1gb it WILL hit disc more often than it needs.
Slow discs, particularly a express problem because most people do not bother to get a proper disc layout. THen they run a sQL database againnst a slow 200 IOPS end user disc where - depending on need - a SQL database wants MANY spindles or an SSD (typical SSD these days has 40.000 IOPS).
That is it at the end - plus possibly really bad SQL. Typical filter error: somefomula(field) LIKE value, which means "forget your index, please, make a table scan and calculate someformula(field) before checking".
First, SQL Server Express is not the best edition to your requierement. Get a Developer's Edition to test it. Its exactly like the Enterprise but free if you dont use on "production".
About the performance, there are so many things involved here, and you can improve it using, since indexes until partitioning. We need more info to provide help
Before Optimizing your SQL queries, you need to find the hotspot of the queries. Usually you can use SQL Profiler to do this on SQL Server. For Express edition, there's no such tool. But you can walk around by using a few queries:
Return all renct query:
SELECT *
FROM sys.dm_exec_query_stats order by total_worker_time DESC;
Return only top time consuming queries:
SELECT total_worker_time, execution_count, last_worker_time, dest.TEXT
FROM sys.dm_exec_query_stats AS deqs
CROSS APPLY sys.dm_exec_sql_text(deqs.sql_handle) AS dest
ORDER BY total_worker_time DESC;
Now you should know which query needs to be optimized.
May be poor indexes,Poor design of database, may not apply normalization,unwanted column indexes,poor queries which take much time to execute.
SQLExpress is built for testing purposes and the performance is directly limited by Microsoft, If you use it in a production environment you may want to get a license for SQL Server.
Have a look here SQL Express for production?