Header download file

If P is greater than X then the number of bytes stored on the index b-tree page is K if K is less than or equal to X or M otherwise. The number of bytes stored on the index page is never less than M. The overflow thresholds are designed to give a minimum fanout of 4 for index b-trees and to make sure enough of the payload is on the b-tree page that the record header can usually be accessed without consulting an overflow page.

In hindsight, the designer of the SQLite b-tree logic realized that these thresholds could have been made much simpler. However, the computations cannot be changed without resulting in an incompatible file format. And the current computations work well, even if they are a little complex. When the payload of a b-tree cell is too large for the b-tree page, the surplus is spilled onto overflow pages.

Overflow pages form a linked list. The first four bytes of each overflow page are a big-endian integer which is the page number of the next page in the chain, or zero for the final page in the chain.

The fifth byte through the last usable byte are used to hold overflow content. Other page types in the database typically have pointers from parent to child. For example, an interior b-tree page contains pointers to its child b-tree pages and an overflow chain has a pointer from earlier to later links in the chain. A ptrmap page contains linkage information going in the opposite direction, from child to parent.

Ptrmap pages must exist in any database file which has a non-zero largest root b-tree page value at offset 52 in the database header. If the largest root b-tree page value is zero, then the database must not contain ptrmap pages. In a database with ptrmap pages, the first ptrmap page is page 2. A ptrmap page consists of an array of 5-byte entries.

Let J be the number of 5-byte entries that will fit in the usable space of a page. And so forth for the entire database file. In a database that uses ptrmap pages, all pages at locations identified by the computation in the previous paragraph must be ptrmap page and no other page may be a ptrmap page.

Except, if the byte-lock page happens to fall on the same page number as a ptrmap page, then the ptrmap is moved to the following page for that one case.

Each 5-byte entry on a ptrmap page provides back-link information about one of the pages that immediately follow the pointer map. And so forth. Each 5-byte ptrmap entry consists of one byte of "page type" information followed by a 4-byte big-endian page number.

Five page types are recognized:. In any database file that contains ptrmap pages, all b-tree root pages must come before any non-root b-tree page, cell payload overflow page, or freelist page. This restriction ensures that a root page will never be moved during an auto-vacuum or incremental-vacuum.

The foregoing text describes low-level aspects of the SQLite file format. The b-tree mechanism provides a powerful and efficient means of accessing a large data set. This section will describe how the low-level b-tree layer is used to implement higher-level SQL capabilities.

The data for a table b-tree leaf page and the key of an index b-tree page was characterized above as an arbitrary sequence of bytes. The prior discussion mentioned one key being less than another, but did not define what "less than" meant. The current section will address these omissions. Payload, either table b-tree data or index b-tree keys, is always in the "record format". The record format defines a sequence of values corresponding to columns in a table or index.

The record format specifies the number of columns, the datatype of each column, and the content of each column. The record format makes extensive use of the variable-length integer or varint representation of bit signed integers defined above. A record contains a header and a body, in that order. The header begins with a single varint which determines the total number of bytes in the header. The varint value is the size of the header in bytes including the size varint itself.

Following the size varint are one or more additional varints, one per column. These additional varints are called "serial type" numbers and determine the datatype of each column, according to the following chart:.

The header size varint and serial type varints will usually consist of a single byte. The serial type varints for large strings and BLOBs might extend to two or three byte varints, but that is the exception rather than the rule.

The varint format is very efficient at coding the record header. The values for each column in the record immediately follow the header. For serial types 0, 8, 9, 12, and 13, the value is zero bytes in length. If all columns are of these types then the body section of the record is empty. A record might have fewer values than the number of columns in the corresponding table.

Missing values at the end of the record are filled in using the default value for the corresponding columns defined in the table schema. The order of keys in an index b-tree is determined by the sort order of the records that the keys represent.

Record comparison progresses column by column. Columns of a record are examined from left to right. The first pair of columns that are not equal determines the relative order of the two records.

The sort order of individual columns is as follows:. A collating function for each column is necessary in order to compute the order of text fields. SQLite defines three built-in collating functions:. Each ordinary SQL table in the database schema is represented on-disk by a table b-tree. Each entry in the table b-tree corresponds to a row of the SQL table. The rowid of the SQL table is the bit signed integer key for each entry in the table b-tree. The content of each SQL table row is stored in the database file by first combining the values in the various columns into a byte array in the record format, then storing that byte array as the payload in an entry in the table b-tree.

The order of values in the record is the same as the order of columns in the SQL table definition. If the affinity of a column is REAL and that column contains a value that can be converted to an integer without loss of information if the value contains no fractional part and is not too large to be represented as an integer then the column may be stored in the record as an integer. SQLite will convert the value back to floating point when extracting it from the record.

The first example above is the preferred definition of the table, of course. Each entry in the index b-tree corresponds to a single row in the associated SQL table. The key to an index b-tree is a record composed of the columns that are being indexed followed by the key of the corresponding table row.

Because every row in the table has a unique row key, all keys in an index are unique. In a normal index, there is a one-to-one mapping between rows in a table and entries in each index associated with that table. Corresponding rows in the index and table b-trees share the same rowid or primary key values and contain the same value for all indexed columns.

As an example, consider the following SQL:. Each row in the ex25ce index is a record with these columns: c, e, d, a. The first two columns are the columns being indexed, c and e. The remaining columns are the primary key of the corresponding table row. Normally, the primary key would be columns d, c, and a, but because column c already appears earlier in the index, it is omitted from the key suffix. The ex25acde example above demonstrates this.

Each entry in the ex25acde index consists of only the columns a, c, d, and e, in that order. Each row in ex25ae contains five columns: a, e, d, c, a. The "a" column is repeated since the first occurrence of "a" has a collating function of "nocase" and the second has a collating sequence of "binary". If the "a" column is not repeated and if the table contains two or more entries with the same "e" value and where "a" differs only in case, then all of those table entries would correspond to a single entry in the index, which would break the one-to-one correspondence between the table and the index.

This b-tree is known as the "schema table" since it stores the complete database schema. The 'table' string is used for both ordinary and virtual tables. For rows that define views, triggers, and virtual tables, the rootpage column is 0 or NULL. The text is usually a copy of the original statement used to create the object but with normalizations applied so that the text conforms to the following rules:.

That name is just a convention used by the database implementation. Because the name of the schema table does not appear anywhere in the file format, the meaning of the database file is not changed if the application chooses to refer to the schema table by one of these alternative names. Such tables store database statistics gathered by the ANALYZE command and used by the query planner to help determine the best algorithm to use for each query.

The first integer in this list is the approximate number of rows in the index. The number of rows in the index is the same as the number of rows in the table, except for partial indexes. The second integer is the approximate number of rows in the index that have the same value in the first column of the index. The third integer is the number number of rows in the index that have the same value for the first two columns.

If the index is unique, then the last integer will be 1. The list of integers in the stat column can optionally be followed by arguments, each of which is a sequence of non-space characters. All arguments are preceded by a single space. Unrecognized arguments are silently ignored.

If the "unordered" argument is present, then the query planner assumes that the index is unordered and will not use the index for a range query or for sorting. New text tokens may be added to the end of the stat column in future enhancements to SQLite. For compatibility, unrecognized tokens at the end of the stat column are silently ignored.

Let C be the number of rows in the index. Then the sampled rows are given by. The variable i in the previous expression varies between 0 and 9. Conceptually, the index space is divided into 10 uniform buckets and the samples are the middle row from each bucket. The rollback journal is a file associated with each SQLite database file that holds information used to restore the database file to its initial state during the course of a transaction. The rollback journal file is always located in the same directory as the database file and has the same name as the database file but with the string " -journal " appended.

There can only be a single rollback journal associated with a give database and hence there can only be one write transaction open against a single database at one time. If a transaction is aborted due to an application crash, an operating system crash, or a hardware power failure or crash, then the database may be left in an inconsistent state. The next time SQLite attempts to open the database file, the presence of the rollback journal file will be detected and the journal will be automatically played back to restore the database to its state at the start of the incomplete transaction.

Add an EditorConfig to a project or solution if you do not already have one. Set the value of the rule to equal the header text you would like applied. You cannot have explicit multilines in an EditorConfig and will need to use the Unix newline character to insert new lines. To apply the file header to an entire project or solution, select Project or Solution under the Fix all occurrences in: option. At least this is what Chrome does when the result of window. Show 1 more comment. Good Generic Code.

Thanks leo. Its helpful. Also what do you suggest adding window. The filename will be wrong if the content disposition specifies a non-UTF8 filename. So, after I get the responseText and everything is Ok, I redirect browser like this: window. Pedro Sousa Pedro Sousa 6 6 silver badges 11 11 bronze badges. Isn't this dangerous security-wise? I would think so because anybody can call download.

Since the access has reached a PHP script, htaccess now stops its duty. One should always sanitise the requested file to be read — Prof. Show 2 more comments. I prefer location. Telmo Dias Telmo Dias 3, 2 2 gold badges 31 31 silver badges 42 42 bronze badges. Alain Cruz Alain Cruz 3, 3 3 gold badges 19 19 silver badges 37 37 bronze badges. Jemil Oyebisi Jemil Oyebisi 7 7 silver badges 8 8 bronze badges. Decoding a filename from the header is a little bit more complex Jaime 4, 2 2 gold badges 19 19 silver badges 42 42 bronze badges.

Lumic Lumic 41 2 2 bronze badges. Please format your entire code block and provide some additional explanation to your process for future reader benefit.

You can just make the a tag hidden and populate the href dynamically. First you need to separate the page processing from the results download. For example, this can be a page that prints the results of a table calculated in the ajax call. I hope this solution can be useful for many, as it was for me. Ryan Dooley Ryan Dooley 3 3 silver badges 14 14 bronze badges.

Sign up or log in Sign up using Google. This is not a bug! IE stores downloads in the Temporary Internet Files folder until the download is complete. I know this because once I downloaded a huge file to My Documents, but the Download Dialog box put it in the Temp folder and moved it at the end.

Just think about it. If IE requires the file to be downloaded to the Temp folder, setting the Cache-Control and Pragma headers will cause an error! I hope this saves someone some time! We encountered a situation where the script accessed by the redirection wasn't loading the session correctly because the precedent script hadn't the time to update it we used a database handler. If you want to remove a header and keep it from being sent as part of the header response, just provide nothing as the header value after the header name.

For example My files are in a compressed state bz2. When the user clicks the link, I want them to get the uncompressed version of the file. After decompressing the file, I ran into the problem, that the download dialog would always pop up, even when I told the dialog to 'Always perform this operation with this file type'.

As I found out, the problem was in the header directive 'Content-Disposition', namely the 'attachment' directive. If you want your browser to simulate a plain link to a file, either change 'attachment' to 'inline' or omit it alltogether and you'll be fine.

This took me a while to figure out and I hope it will help someone else out there, who runs into the same problem. This is helpful if you want a javascript or similar client-side function to execute a server-side function without refreshing or changing the current webpage. Great for updating database, setting global variables, etc.

I just want to add, becuase I see here lots of wrong formated headers. All used headers have first letters uppercase, so you MUST follow this. Location header MUST be absolute uri with scheme, domain, port, path, etc.

But the strange behaviour of dirname is a problem for URL ending by a directory without file name! The user is now asked for a md5 password instead of keeping it in the code directly. There is some part in French because it's my native language so modify it as you want. Y OK" and later "Status: Other Status", the server should deal the situation i also realized header don't have the ability to force replace via the second paramter the headers sent by server, at least in cgi mode cheers.