Table Size

[DaveM]

Re: Table Size

Robin,

I "think" the "header" is the header of the dbf file. Names of the fields and stuff. I would think a cdx file would have something similar(not sure though). Try opening a dbf file with notepad and see what it looks like? CDX??


.

[csda1]

Re: Table Size

Hi Robin,

My mistake. I meant FPT (which is the memo file as referred to in the text) and have corrected it on the posting.

The dbf header has information on the number of records, and record structure (fields) and a few other miscellaneous info.

[MoGrace]

Re: Table Size

Thanks Ira - I thought the CDX was for indexes? What constitutes the header value?

[csda1]

Re: Table Size

Each dbf file contains a fixed record size, so that most fields take up their width as described below.

Memo, Blobs and Memo-like fields use a 10 byte pointer field in the dbf file
Dates use 8 characters
Long time uses 17 bytes
Short time uses 8 bytes
Logical uses 1 byte
Character, Numbers use their width
and 1 extra byte per record for the mark/delete record flag

Compute the total size of the record (also displayed when modifying the structure) and multiple by the total # of records and add the header, which is limited to a maximum of 65535 bytes, but is more typically less than 512 bytes.

That total size must be less than 2 Gigs.

In addition, all bytes stored in the FPT (memo file) limit the size of the memo file to 2 Gigs as well (including older copies of each entry that were smaller than the current size of the memo entry)

[MoGrace]

Re: Table Size

Is it possible to estimate how many records a table can hold before it might reach this limitation? IOW does the record size and number of records in the table determine the file size alone or is there also some other factor? Does a record with 10 fields of 10 characters each actually equal 100 bytes? I do know that even an empty file takes up 1 kb, but past that, how do you estimate this?

[Dave Mac Callum]

Re: Table Size

Funny thing,

I just took a 15 meg dbf file(packed) and split it into 2 tables, got rid of a couple fields that had never been used and now the 2 tables are under 10 megabytes. also to connect the 2 properly within sets I have 3 fields that are duplicates.

Dave

Hi Dave,

I need some help here before I go down the wrong road.

I have a set consisting 5 tables, typically count field of 30 and record size < 500. It somehow seemed easier to control smaller tables. However when i need to calculate in an emdebbed browse, I cannot use cross-table fields in the calculation, it seems as though all the fields required in the calculation ne to be in a single table. (?).

Do you think it is better to have a single table even though it may have a field count of > 200 and record size > 1000 ? This will allow me to calculate as above. Or are there dangers in making a single large table ?

Looking forward

[andymeer]

Re: Table Size

Hi All

Just an update to this post, my customer reached the 2,147,483,648 bytes limit sooner than expected. I managed to remove some old records and I have created a archive routine which is going to be applied this weekend.

When the table reaches 2,147,483,648 bytes it just stops adding any more records to the table.

so in conclusion the table limit is : 2,147,483,648 bytes
what happens when it reaches : 2,147,483,648 bytes cannot add any more records

Andy

[G Gabriel]

Re: Table Size

One thing that has confused me a little if the file, is now 2,050,828kb isn't this file already over 2gb?

No, but you are getting very close.

2 GB= 2,147,483,648
Got 96,655,648 left

P.S.
These limits are abritrary and cautionary, but if I were you, I wouldn't push my luck.

[DaveM]

Re: Table Size

Funny thing,

I just took a 15 meg dbf file(packed) and split it into 2 tables, got rid of a couple fields that had never been used and now the 2 tables are under 10 megabytes. also to connect the 2 properly within sets I have 3 fields that are duplicates.

Dave

[jmatienza]

Re: Table Size

One thing that has confused me a little if the file, is now 2,050,828kb isn't this file already over 2gb?

Andy

Byte capacities are calculated on doublings of 2. In other words, a kilobyte isn't exactly 1,000 bytes; it's actually 2 raised to the 10th power, or 1,024 bytes. Two KB is 2 raised to the next step, the 11th power, or 2,048 bytes. Four KB is 2 raised to the 12th power, or 4,096 bytes. (Note that in this progression there is no such thing as "3 KB".) And so on.

2 gigabytes is actually 2 raised to the 31st power, or 2,147,483,648 bytes.

Based on this calculation, you haven't reached the limit yet.

[andymeer]

Re: Table Size

Hi All

Thanks for your replies, It looks as if I need to get this sorted out ASAP. One thing that has confused me a little if the file, is now 2,050,828kb isn't this file already over 2gb?

Andy

[csda1]

Re: Table Size

Andy,

The file limit of 2 Gig applies to 1 file, so if you link a bunch of smaller tables, or put different memo fields in their own linked tables (recommended, but let's not get in that discussion here), then the sizes can normally be kept under the 2 Gig limit. Or use an SQL table, and there is no practical limit.

[Tim Kiebert]

Re: Table Size

I found this at the following link.

The file format can also be an issue. The maximum size of a .DBF file is
2GB. That is because the file has to contain offsets to various other
locations within the file, and those offsets are based on 32-bit
integers. No software that is writing to a .DBF file can get around
this. Ideally, the software should detect when it it has written as much
data that the output file format can accommodate, refuse to write any
more, close the file, and inform the user of the situation. If the
software keeps writing then all it will do is convert a maximum-sized
file that is at least usable into a corrupt file that may contain more
data but is unusable because of messed up offset values.

[Peter.Wayne]

Re: Table Size

Well, I think I'm wrong. According to Microsoft, who should know, the maximum size of a Visual Foxpro dbf file is 2 GB, independent of the OS system maximum file size:
http://msdn2.microsoft.com/en-us/lib...w9(VS.80).aspx

[MikeC]

Re: Table Size

Just did a little search--NTFS supports 16 Terrabyte file size.


Mike