I'm developing a Java web application that deals with large amounts of text (HTML code strings encoded using base64), which I need to save in my database. I'm using Firebird 2.0, and every time I try to insert a new record with strings longer than 32767 characters, I receive the following error:
GDS Exception. 335544726. Error reading data from the connection.
I have done some research about it, and apparently this is the character limit for Firebird, both for query strings and records in the database. I have tried a couple of things, like splitting the string in the query and then concatenating the parts, but it didn't work. Does anyone know any workarounds for this issue?
If you need to save large amount of text data in the database - just use BLOB fields. Varchar field size is limited to 32Kb.
For better performance you can use binary BLOBs and save there zipped data.
Firebird query strings are limited to 64 kilobytes in Firebird 2.5 and earlier. The maximum length of a varchar field is 32766 byte (which means it can only store 8191 characters when using UTF-8!). The maximum size of a row (with blobs counting for 8 bytes) is 64 kilobytes as well.
If you want to store values longer than 32 kilobytes, you need to use a BLOB SUB_TYPE TEXT, and you need to use a prepared statement to set the value.
Related
In working on a project, where:
A dataset is collected every 10 seconds, which is stored in an SQlite file on an server.
After being processed, the data is sent to an SQL-Database every 5 minutes.
Afterwards the data in the SQlite file, which isn't needed anymore, gets deleted.
The collecting of the data continues and at the moment the id doens't get reset.
I didn't get how much an integer in SQLite can store according to the documentation (https://www.sqlite.org/datatype3.html).
In MySQL-Databases the maximum value of an interger column is 2.147.483.647. If my script would run for 10 years the id would be 31.449.600. Although this would be much lower less than the maximum, I wondered,
if there is any problem with storing high values in SQlite.
Could this affect the performance?
That page mentions that integer numbers can be stored in up to 8 bytes, i.e., 64 bits.
As mentioned elsewhere, this means that the largest allowed integer is 9,223,372,036,854,775,807.
An integer in SQLite can store values up to 9223372036854775807 (8 Bytes signed so 63 bits as 1 bit is for the sign), which is the same as a MySQL BIGINT (which is in addition to the Standard INT).
First off, I know that in general having large numbers of wide columns is a bad idea, but this is the format I'm constrained to.
I have an application that imports CSV files into a staging table before manipulating them and inserting/updating values in the database. The staging table is created on the fly and has a variable number of NVARCHAR colums into which the file is imported, plus two INT columns used as row IDs.
One particular file I have to import is about 450 columns wide. With the 24 byte pointer used in a large NVARCHAR column, this adds up to around 10k by my calculations, and I get the error Cannot create a row of size 11166 which is greater than the allowable maximum row size of 8060.
Is there a way around this or are my only choices modifying the importer to split the import or removing columns from the file?
You can use text/ntext which uses 16 bytes pointer. Whereas varchar/nvarchar uses 24bytes pointer.
NVARCHAR(max) or NTEXT can store the data more than 8kb but a record size can not be greater than 8kb till SQL Server 2012. If Data is not fitted in 8kb page size then the data of larger column is moved to another page and a 24 bytes(if data type is varchar/nvarchar) pointer is used to store as reference pointer in main column. if it is text/ntext data type then 16 bytes poiner is used.
For Details you can Visit at following links :
Work around SQL Server maximum columns limit 1024 and 8kb record size
or
http://msdn.microsoft.com/en-us/library/ms186939(v=sql.90).aspx
If you are using SQL Server 2005, 2008 or 2012, you should be able to use NVARCHAR(max) or NTEXT which would be larger than 8,000 characters. MAX will give you 2^31 - 1 characters:
http://msdn.microsoft.com/en-us/library/ms186939(v=sql.90).aspx
I agree that Varchar or nvarchar (Max) is a good solution and will probably work for you, but completeness I will suggest that you can also create more than one table with the two tables having a One-to-One relationship.
I'm storing data in a varbinary(max) column and, for client performance reasons, chunking writes through the ".WRITE()" function using SQL Server 2005. This works great but, due to the side effects, I want to avoid the varbinary column dynamically sizing during each append.
What I'd like to do is optimize this by pre-allocating the varbinary column to the size I want. For example if I'm going to drop 2MB into the column I would like to 'allocate' the column first, then .WRITE the real data using offset/length parameters.
Is there anything in SQL that can help me here? Obviously I don't want to send a null byte array to the SQL server, as this would partially defeat the purpose of the .WRITE optimization.
If you're using a (MAX) data type, then anything above 8K goes into row overflow storage, not the in-page storage. So you just need to put in enough data to get it up to the 8K for the row, making that take up the in-page allocation for the row, and the rest goes into row-overflow storage anyway. There's some more here.
If you want to pre-allocate everything, including the row overflow data, you can use something akin to (example does 10000 bytes):
SELECT CONVERT([varbinary](MAX), REPLICATE(CONVERT(varchar(MAX), '0'), 10000))
First of all kudos to the answer provided - this was a great help! However, there is one slight change that you may want to consider. The code above actually allocates the varbinary field with a converted zero character (hex code 0x30). This may not be what you actually want, particularly if you want to perform binary operations on the field later. What I think is more useful is to allocate the field with a NUL value (hex code 0x00) so that all the bits are turned off by default. To do this, simply make the following correction:
SELECT CONVERT([varbinary](MAX), REPLICATE(CONVERT(varchar(MAX), CHAR(0)), 10000))
Disclaimer: I'm very new to SQL and databases in general.
I need to create a field that will store a maximum of 32 characters of text data. Does "VARCHAR(32)" mean that I have exactly 32 characters for my data? Do I need to reserve an extra character for null-termination?
I conducted a simple test and it seems that this is a WYSIWYG buffer. However, I wanted to get a concrete answer from people who actually know what they're doing.
I have a C[++] background, so this question is raising alarm bells in my head.
Yes, you have 32 characters at your disposal. SQL does not concern itself with nul terminated strings like some programming languages do.
Your VARCHAR specification size is the max size of your data, so in this case, 32 characters. However, VARCHARS are a dynamic field, so the actual physical storage used is only the size of your data, plus one or two bytes.
If you put a 10-character string into a VARCHAR(32), the physical storage will be 11 or 12 bytes (the manual will tell you the exact formula).
However, when MySQL is dealing with result sets (ie. after a SELECT), 32 bytes will be allocated in memory for that field for every record.
SQL databases seem to be the cornerstone of most software. However, it seems optimized for textual data. In fact when doing any queries involving numerical data, integers specifically, it seems inefficient that the numbers are getting converted to text and then back to native formats both ways between the application and the database. This same inefficiency seems to apply to BLOB data as well. My understanding is that even with something like Linq to SQL, this two way conversion is occuring in the background.
Are there general ways to bypass this overhead with SQL? Are there certain database management systems that handle this more efficiently than others (ie, with non-standard extensions/API's)?
Clarification. In the following select statement, the list of numbers after IN could be more easily passed as a raw array of int, but there seems to be no way of achieving that optimization level.
SELECT foo FROM bar WHERE baz IN (23, 34, 45, 9854004, ...)
Don't suppose. Measure.
Format conversion is not likely to be a measurable cost for database work, unless you are misusing the database as an arithmetic engine.
The IO cost for LOBs, especially for CLOBS with character conversion, can become significant; the remedy here, once you know that the simplest thing that might work actually has a noticeable performance impact, is to minimize the number of times you copy the LOB data. Use whatever SQL parameter binding style allows you to transfer the data directly between its point of creation or use, and the database -- often this is binding the LOB to a stream or I/O channel.
But don't do this until you have a way to measure the impact, and have measurements showing that this is your bottleneck.
Numerical data in a database is not stored as text. I guess it depends on the database, but it certainly doesn't have to be and isn't.
BLOBs are stored exactly how you set them -- by definition, the DB has no way to interpret the information -- I guess it could compress if it found that to be useful. BLOBs are not translated into text.
Here's how Oracle stores numbers:
http://download.oracle.com/docs/cd/B28359_01/server.111/b28318/datatype.htm#i16209
Internal Numeric Format
Oracle Database stores numeric data in variable-length format. Each value is stored in scientific notation, with 1 byte used to store the exponent and up to 20 bytes to store the mantissa. The resulting value is limited to 38 digits of precision. Oracle Database does not store leading and trailing zeros. For example, the number 412 is stored in a format similar to 4.12 x 102, with 1 byte used to store the exponent(2) and 2 bytes used to store the three significant digits of the mantissa(4,1,2). Negative numbers include the sign in their length.
MySQL info here:
http://dev.mysql.com/doc/refman/5.0/en/numeric-types.html
Look at the table -- a TINYINT is represented in 1 byte (range -128 - 127), not possible if stored as text.
EDIT: With the clarification -- I would say use the API in your language that looks something like this (pseudocode)
stmt = conn.Prepare("SELECT * FROM TABLE where x in (?, ?, ?)");
stmt.SetInt(0, x);
stmt.SetInt(1, y);
stmt.SetInt(2, z);
I don't believe that the underlying protocols use text for the transport of parameters.