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diff --git a/doc/src/sgml/ref/copy.sgml b/doc/src/sgml/ref/copy.sgml new file mode 100644 index 0000000..63afa0d --- /dev/null +++ b/doc/src/sgml/ref/copy.sgml @@ -0,0 +1,1081 @@ +<!-- +doc/src/sgml/ref/copy.sgml +PostgreSQL documentation +--> + +<refentry id="sql-copy"> + <indexterm zone="sql-copy"> + <primary>COPY</primary> + </indexterm> + + <refmeta> + <refentrytitle>COPY</refentrytitle> + <manvolnum>7</manvolnum> + <refmiscinfo>SQL - Language Statements</refmiscinfo> + </refmeta> + + <refnamediv> + <refname>COPY</refname> + <refpurpose>copy data between a file and a table</refpurpose> + </refnamediv> + + <refsynopsisdiv> +<synopsis> +COPY <replaceable class="parameter">table_name</replaceable> [ ( <replaceable class="parameter">column_name</replaceable> [, ...] ) ] + FROM { '<replaceable class="parameter">filename</replaceable>' | PROGRAM '<replaceable class="parameter">command</replaceable>' | STDIN } + [ [ WITH ] ( <replaceable class="parameter">option</replaceable> [, ...] ) ] + [ WHERE <replaceable class="parameter">condition</replaceable> ] + +COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable class="parameter">column_name</replaceable> [, ...] ) ] | ( <replaceable class="parameter">query</replaceable> ) } + TO { '<replaceable class="parameter">filename</replaceable>' | PROGRAM '<replaceable class="parameter">command</replaceable>' | STDOUT } + [ [ WITH ] ( <replaceable class="parameter">option</replaceable> [, ...] ) ] + +<phrase>where <replaceable class="parameter">option</replaceable> can be one of:</phrase> + + FORMAT <replaceable class="parameter">format_name</replaceable> + FREEZE [ <replaceable class="parameter">boolean</replaceable> ] + DELIMITER '<replaceable class="parameter">delimiter_character</replaceable>' + NULL '<replaceable class="parameter">null_string</replaceable>' + HEADER [ <replaceable class="parameter">boolean</replaceable> | MATCH ] + QUOTE '<replaceable class="parameter">quote_character</replaceable>' + ESCAPE '<replaceable class="parameter">escape_character</replaceable>' + FORCE_QUOTE { ( <replaceable class="parameter">column_name</replaceable> [, ...] ) | * } + FORCE_NOT_NULL ( <replaceable class="parameter">column_name</replaceable> [, ...] ) + FORCE_NULL ( <replaceable class="parameter">column_name</replaceable> [, ...] ) + ENCODING '<replaceable class="parameter">encoding_name</replaceable>' +</synopsis> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para> + <command>COPY</command> moves data between + <productname>PostgreSQL</productname> tables and standard file-system + files. <command>COPY TO</command> copies the contents of a table + <emphasis>to</emphasis> a file, while <command>COPY FROM</command> copies + data <emphasis>from</emphasis> a file to a table (appending the data to + whatever is in the table already). <command>COPY TO</command> + can also copy the results of a <command>SELECT</command> query. + </para> + + <para> + If a column list is specified, <command>COPY TO</command> copies only + the data in the specified columns to the file. For <command>COPY + FROM</command>, each field in the file is inserted, in order, into the + specified column. Table columns not specified in the <command>COPY + FROM</command> column list will receive their default values. + </para> + + <para> + <command>COPY</command> with a file name instructs the + <productname>PostgreSQL</productname> server to directly read from + or write to a file. The file must be accessible by the + <productname>PostgreSQL</productname> user (the user ID the server + runs as) and the name must be specified from the viewpoint of the + server. When <literal>PROGRAM</literal> is specified, the server + executes the given command and reads from the standard output of the + program, or writes to the standard input of the program. The command + must be specified from the viewpoint of the server, and be executable + by the <productname>PostgreSQL</productname> user. When + <literal>STDIN</literal> or <literal>STDOUT</literal> is + specified, data is transmitted via the connection between the + client and the server. + </para> + + <para> + Each backend running <command>COPY</command> will report its progress + in the <structname>pg_stat_progress_copy</structname> view. See + <xref linkend="copy-progress-reporting"/> for details. + </para> + </refsect1> + + <refsect1> + <title>Parameters</title> + + <variablelist> + <varlistentry> + <term><replaceable class="parameter">table_name</replaceable></term> + <listitem> + <para> + The name (optionally schema-qualified) of an existing table. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><replaceable class="parameter">column_name</replaceable></term> + <listitem> + <para> + An optional list of columns to be copied. If no column list is + specified, all columns of the table except generated columns will be + copied. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><replaceable class="parameter">query</replaceable></term> + <listitem> + <para> + A <link linkend="sql-select"><command>SELECT</command></link>, + <link linkend="sql-values"><command>VALUES</command></link>, + <link linkend="sql-insert"><command>INSERT</command></link>, + <link linkend="sql-update"><command>UPDATE</command></link>, or + <link linkend="sql-delete"><command>DELETE</command></link> command whose results are to be + copied. Note that parentheses are required around the query. + </para> + <para> + For <command>INSERT</command>, <command>UPDATE</command> and + <command>DELETE</command> queries a RETURNING clause must be provided, + and the target relation must not have a conditional rule, nor + an <literal>ALSO</literal> rule, nor an <literal>INSTEAD</literal> rule + that expands to multiple statements. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><replaceable class="parameter">filename</replaceable></term> + <listitem> + <para> + The path name of the input or output file. An input file name can be + an absolute or relative path, but an output file name must be an absolute + path. Windows users might need to use an <literal>E''</literal> string and + double any backslashes used in the path name. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>PROGRAM</literal></term> + <listitem> + <para> + A command to execute. In <command>COPY FROM</command>, the input is + read from standard output of the command, and in <command>COPY TO</command>, + the output is written to the standard input of the command. + </para> + <para> + Note that the command is invoked by the shell, so if you need to pass + any arguments to shell command that come from an untrusted source, you + must be careful to strip or escape any special characters that might + have a special meaning for the shell. For security reasons, it is best + to use a fixed command string, or at least avoid passing any user input + in it. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>STDIN</literal></term> + <listitem> + <para> + Specifies that input comes from the client application. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>STDOUT</literal></term> + <listitem> + <para> + Specifies that output goes to the client application. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><replaceable class="parameter">boolean</replaceable></term> + <listitem> + <para> + Specifies whether the selected option should be turned on or off. + You can write <literal>TRUE</literal>, <literal>ON</literal>, or + <literal>1</literal> to enable the option, and <literal>FALSE</literal>, + <literal>OFF</literal>, or <literal>0</literal> to disable it. The + <replaceable class="parameter">boolean</replaceable> value can also + be omitted, in which case <literal>TRUE</literal> is assumed. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>FORMAT</literal></term> + <listitem> + <para> + Selects the data format to be read or written: + <literal>text</literal>, + <literal>csv</literal> (Comma Separated Values), + or <literal>binary</literal>. + The default is <literal>text</literal>. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>FREEZE</literal></term> + <listitem> + <para> + Requests copying the data with rows already frozen, just as they + would be after running the <command>VACUUM FREEZE</command> command. + This is intended as a performance option for initial data loading. + Rows will be frozen only if the table being loaded has been created + or truncated in the current subtransaction, there are no cursors + open and there are no older snapshots held by this transaction. It is + currently not possible to perform a <command>COPY FREEZE</command> on + a partitioned table. + </para> + <para> + Note that all other sessions will immediately be able to see the data + once it has been successfully loaded. This violates the normal rules + of MVCC visibility and users specifying should be aware of the + potential problems this might cause. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>DELIMITER</literal></term> + <listitem> + <para> + Specifies the character that separates columns within each row + (line) of the file. The default is a tab character in text format, + a comma in <literal>CSV</literal> format. + This must be a single one-byte character. + This option is not allowed when using <literal>binary</literal> format. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>NULL</literal></term> + <listitem> + <para> + Specifies the string that represents a null value. The default is + <literal>\N</literal> (backslash-N) in text format, and an unquoted empty + string in <literal>CSV</literal> format. You might prefer an + empty string even in text format for cases where you don't want to + distinguish nulls from empty strings. + This option is not allowed when using <literal>binary</literal> format. + </para> + + <note> + <para> + When using <command>COPY FROM</command>, any data item that matches + this string will be stored as a null value, so you should make + sure that you use the same string as you used with + <command>COPY TO</command>. + </para> + </note> + + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>HEADER</literal></term> + <listitem> + <para> + Specifies that the file contains a header line with the names of each + column in the file. On output, the first line contains the column + names from the table. On input, the first line is discarded when this + option is set to <literal>true</literal> (or equivalent Boolean value). + If this option is set to <literal>MATCH</literal>, the number and names + of the columns in the header line must match the actual column names of + the table, in order; otherwise an error is raised. + This option is not allowed when using <literal>binary</literal> format. + The <literal>MATCH</literal> option is only valid for <command>COPY + FROM</command> commands. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>QUOTE</literal></term> + <listitem> + <para> + Specifies the quoting character to be used when a data value is quoted. + The default is double-quote. + This must be a single one-byte character. + This option is allowed only when using <literal>CSV</literal> format. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>ESCAPE</literal></term> + <listitem> + <para> + Specifies the character that should appear before a + data character that matches the <literal>QUOTE</literal> value. + The default is the same as the <literal>QUOTE</literal> value (so that + the quoting character is doubled if it appears in the data). + This must be a single one-byte character. + This option is allowed only when using <literal>CSV</literal> format. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>FORCE_QUOTE</literal></term> + <listitem> + <para> + Forces quoting to be + used for all non-<literal>NULL</literal> values in each specified column. + <literal>NULL</literal> output is never quoted. If <literal>*</literal> is specified, + non-<literal>NULL</literal> values will be quoted in all columns. + This option is allowed only in <command>COPY TO</command>, and only when + using <literal>CSV</literal> format. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>FORCE_NOT_NULL</literal></term> + <listitem> + <para> + Do not match the specified columns' values against the null string. + In the default case where the null string is empty, this means that + empty values will be read as zero-length strings rather than nulls, + even when they are not quoted. + This option is allowed only in <command>COPY FROM</command>, and only when + using <literal>CSV</literal> format. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>FORCE_NULL</literal></term> + <listitem> + <para> + Match the specified columns' values against the null string, even + if it has been quoted, and if a match is found set the value to + <literal>NULL</literal>. In the default case where the null string is empty, + this converts a quoted empty string into NULL. + This option is allowed only in <command>COPY FROM</command>, and only when + using <literal>CSV</literal> format. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>ENCODING</literal></term> + <listitem> + <para> + Specifies that the file is encoded in the <replaceable + class="parameter">encoding_name</replaceable>. If this option is + omitted, the current client encoding is used. See the Notes below + for more details. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><literal>WHERE</literal></term> + <listitem> + <para> + The optional <literal>WHERE</literal> clause has the general form +<synopsis> +WHERE <replaceable class="parameter">condition</replaceable> +</synopsis> + where <replaceable class="parameter">condition</replaceable> is + any expression that evaluates to a result of type + <type>boolean</type>. Any row that does not satisfy this + condition will not be inserted to the table. A row satisfies the + condition if it returns true when the actual row values are + substituted for any variable references. + </para> + + <para> + Currently, subqueries are not allowed in <literal>WHERE</literal> + expressions, and the evaluation does not see any changes made by the + <command>COPY</command> itself (this matters when the expression + contains calls to <literal>VOLATILE</literal> functions). + </para> + + </listitem> + </varlistentry> + + </variablelist> + </refsect1> + + <refsect1> + <title>Outputs</title> + + <para> + On successful completion, a <command>COPY</command> command returns a command + tag of the form +<screen> +COPY <replaceable class="parameter">count</replaceable> +</screen> + The <replaceable class="parameter">count</replaceable> is the number + of rows copied. + </para> + + <note> + <para> + <application>psql</application> will print this command tag only if the command + was not <literal>COPY ... TO STDOUT</literal>, or the + equivalent <application>psql</application> meta-command + <literal>\copy ... to stdout</literal>. This is to prevent confusing the + command tag with the data that was just printed. + </para> + </note> + </refsect1> + + <refsect1> + <title>Notes</title> + + <para> + <command>COPY TO</command> can be used only with plain + tables, not views, and does not copy rows from child tables + or child partitions. For example, <literal>COPY <replaceable + class="parameter">table</replaceable> TO</literal> copies + the same rows as <literal>SELECT * FROM ONLY <replaceable + class="parameter">table</replaceable></literal>. + The syntax <literal>COPY (SELECT * FROM <replaceable + class="parameter">table</replaceable>) TO ...</literal> can be used to + dump all of the rows in an inheritance hierarchy, partitioned table, + or view. + </para> + + <para> + <command>COPY FROM</command> can be used with plain, foreign, or + partitioned tables or with views that have + <literal>INSTEAD OF INSERT</literal> triggers. + </para> + + <para> + You must have select privilege on the table + whose values are read by <command>COPY TO</command>, and + insert privilege on the table into which values + are inserted by <command>COPY FROM</command>. It is sufficient + to have column privileges on the column(s) listed in the command. + </para> + + <para> + If row-level security is enabled for the table, the relevant + <command>SELECT</command> policies will apply to <literal>COPY + <replaceable class="parameter">table</replaceable> TO</literal> statements. + Currently, <command>COPY FROM</command> is not supported for tables + with row-level security. Use equivalent <command>INSERT</command> + statements instead. + </para> + + <para> + Files named in a <command>COPY</command> command are read or written + directly by the server, not by the client application. Therefore, + they must reside on or be accessible to the database server machine, + not the client. They must be accessible to and readable or writable + by the <productname>PostgreSQL</productname> user (the user ID the + server runs as), not the client. Similarly, + the command specified with <literal>PROGRAM</literal> is executed directly + by the server, not by the client application, must be executable by the + <productname>PostgreSQL</productname> user. + <command>COPY</command> naming a file or command is only allowed to + database superusers or users who are granted one of the roles + <literal>pg_read_server_files</literal>, + <literal>pg_write_server_files</literal>, + or <literal>pg_execute_server_program</literal>, since it allows reading + or writing any file or running a program that the server has privileges to + access. + </para> + + <para> + Do not confuse <command>COPY</command> with the + <application>psql</application> instruction + <command><link linkend="app-psql-meta-commands-copy">\copy</link></command>. <command>\copy</command> invokes + <command>COPY FROM STDIN</command> or <command>COPY TO + STDOUT</command>, and then fetches/stores the data in a file + accessible to the <application>psql</application> client. Thus, + file accessibility and access rights depend on the client rather + than the server when <command>\copy</command> is used. + </para> + + <para> + It is recommended that the file name used in <command>COPY</command> + always be specified as an absolute path. This is enforced by the + server in the case of <command>COPY TO</command>, but for + <command>COPY FROM</command> you do have the option of reading from + a file specified by a relative path. The path will be interpreted + relative to the working directory of the server process (normally + the cluster's data directory), not the client's working directory. + </para> + + <para> + Executing a command with <literal>PROGRAM</literal> might be restricted + by the operating system's access control mechanisms, such as SELinux. + </para> + + <para> + <command>COPY FROM</command> will invoke any triggers and check + constraints on the destination table. However, it will not invoke rules. + </para> + + <para> + For identity columns, the <command>COPY FROM</command> command will always + write the column values provided in the input data, like + the <command>INSERT</command> option <literal>OVERRIDING SYSTEM + VALUE</literal>. + </para> + + <para> + <command>COPY</command> input and output is affected by + <varname>DateStyle</varname>. To ensure portability to other + <productname>PostgreSQL</productname> installations that might use + non-default <varname>DateStyle</varname> settings, + <varname>DateStyle</varname> should be set to <literal>ISO</literal> before + using <command>COPY TO</command>. It is also a good idea to avoid dumping + data with <varname>IntervalStyle</varname> set to + <literal>sql_standard</literal>, because negative interval values might be + misinterpreted by a server that has a different setting for + <varname>IntervalStyle</varname>. + </para> + + <para> + Input data is interpreted according to <literal>ENCODING</literal> + option or the current client encoding, and output data is encoded + in <literal>ENCODING</literal> or the current client encoding, even + if the data does not pass through the client but is read from or + written to a file directly by the server. + </para> + + <para> + <command>COPY</command> stops operation at the first error. This + should not lead to problems in the event of a <command>COPY + TO</command>, but the target table will already have received + earlier rows in a <command>COPY FROM</command>. These rows will not + be visible or accessible, but they still occupy disk space. This might + amount to a considerable amount of wasted disk space if the failure + happened well into a large copy operation. You might wish to invoke + <command>VACUUM</command> to recover the wasted space. + </para> + + <para> + <literal>FORCE_NULL</literal> and <literal>FORCE_NOT_NULL</literal> can be used + simultaneously on the same column. This results in converting quoted + null strings to null values and unquoted null strings to empty strings. + </para> + + </refsect1> + + <refsect1> + <title>File Formats</title> + + <refsect2> + <title>Text Format</title> + + <para> + When the <literal>text</literal> format is used, + the data read or written is a text file with one line per table row. + Columns in a row are separated by the delimiter character. + The column values themselves are strings generated by the + output function, or acceptable to the input function, of each + attribute's data type. The specified null string is used in + place of columns that are null. + <command>COPY FROM</command> will raise an error if any line of the + input file contains more or fewer columns than are expected. + </para> + + <para> + End of data can be represented by a single line containing just + backslash-period (<literal>\.</literal>). An end-of-data marker is + not necessary when reading from a file, since the end of file + serves perfectly well; it is needed only when copying data to or from + client applications using pre-3.0 client protocol. + </para> + + <para> + Backslash characters (<literal>\</literal>) can be used in the + <command>COPY</command> data to quote data characters that might + otherwise be taken as row or column delimiters. In particular, the + following characters <emphasis>must</emphasis> be preceded by a backslash if + they appear as part of a column value: backslash itself, + newline, carriage return, and the current delimiter character. + </para> + + <para> + The specified null string is sent by <command>COPY TO</command> without + adding any backslashes; conversely, <command>COPY FROM</command> matches + the input against the null string before removing backslashes. Therefore, + a null string such as <literal>\N</literal> cannot be confused with + the actual data value <literal>\N</literal> (which would be represented + as <literal>\\N</literal>). + </para> + + <para> + The following special backslash sequences are recognized by + <command>COPY FROM</command>: + + <informaltable> + <tgroup cols="2"> + <thead> + <row> + <entry>Sequence</entry> + <entry>Represents</entry> + </row> + </thead> + + <tbody> + <row> + <entry><literal>\b</literal></entry> + <entry>Backspace (ASCII 8)</entry> + </row> + <row> + <entry><literal>\f</literal></entry> + <entry>Form feed (ASCII 12)</entry> + </row> + <row> + <entry><literal>\n</literal></entry> + <entry>Newline (ASCII 10)</entry> + </row> + <row> + <entry><literal>\r</literal></entry> + <entry>Carriage return (ASCII 13)</entry> + </row> + <row> + <entry><literal>\t</literal></entry> + <entry>Tab (ASCII 9)</entry> + </row> + <row> + <entry><literal>\v</literal></entry> + <entry>Vertical tab (ASCII 11)</entry> + </row> + <row> + <entry><literal>\</literal><replaceable>digits</replaceable></entry> + <entry>Backslash followed by one to three octal digits specifies + the byte with that numeric code</entry> + </row> + <row> + <entry><literal>\x</literal><replaceable>digits</replaceable></entry> + <entry>Backslash <literal>x</literal> followed by one or two hex digits specifies + the byte with that numeric code</entry> + </row> + </tbody> + </tgroup> + </informaltable> + + Presently, <command>COPY TO</command> will never emit an octal or + hex-digits backslash sequence, but it does use the other sequences + listed above for those control characters. + </para> + + <para> + Any other backslashed character that is not mentioned in the above table + will be taken to represent itself. However, beware of adding backslashes + unnecessarily, since that might accidentally produce a string matching the + end-of-data marker (<literal>\.</literal>) or the null string (<literal>\N</literal> by + default). These strings will be recognized before any other backslash + processing is done. + </para> + + <para> + It is strongly recommended that applications generating <command>COPY</command> data convert + data newlines and carriage returns to the <literal>\n</literal> and + <literal>\r</literal> sequences respectively. At present it is + possible to represent a data carriage return by a backslash and carriage + return, and to represent a data newline by a backslash and newline. + However, these representations might not be accepted in future releases. + They are also highly vulnerable to corruption if the <command>COPY</command> file is + transferred across different machines (for example, from Unix to Windows + or vice versa). + </para> + + <para> + All backslash sequences are interpreted after encoding conversion. + The bytes specified with the octal and hex-digit backslash sequences must + form valid characters in the database encoding. + </para> + + <para> + <command>COPY TO</command> will terminate each row with a Unix-style + newline (<quote><literal>\n</literal></quote>). Servers running on Microsoft Windows instead + output carriage return/newline (<quote><literal>\r\n</literal></quote>), but only for + <command>COPY</command> to a server file; for consistency across platforms, + <command>COPY TO STDOUT</command> always sends <quote><literal>\n</literal></quote> + regardless of server platform. + <command>COPY FROM</command> can handle lines ending with newlines, + carriage returns, or carriage return/newlines. To reduce the risk of + error due to un-backslashed newlines or carriage returns that were + meant as data, <command>COPY FROM</command> will complain if the line + endings in the input are not all alike. + </para> + </refsect2> + + <refsect2> + <title>CSV Format</title> + + <para> + This format option is used for importing and exporting the Comma + Separated Value (<literal>CSV</literal>) file format used by many other + programs, such as spreadsheets. Instead of the escaping rules used by + <productname>PostgreSQL</productname>'s standard text format, it + produces and recognizes the common CSV escaping mechanism. + </para> + + <para> + The values in each record are separated by the <literal>DELIMITER</literal> + character. If the value contains the delimiter character, the + <literal>QUOTE</literal> character, the <literal>NULL</literal> string, a carriage + return, or line feed character, then the whole value is prefixed and + suffixed by the <literal>QUOTE</literal> character, and any occurrence + within the value of a <literal>QUOTE</literal> character or the + <literal>ESCAPE</literal> character is preceded by the escape character. + You can also use <literal>FORCE_QUOTE</literal> to force quotes when outputting + non-<literal>NULL</literal> values in specific columns. + </para> + + <para> + The <literal>CSV</literal> format has no standard way to distinguish a + <literal>NULL</literal> value from an empty string. + <productname>PostgreSQL</productname>'s <command>COPY</command> handles this by quoting. + A <literal>NULL</literal> is output as the <literal>NULL</literal> parameter string + and is not quoted, while a non-<literal>NULL</literal> value matching the + <literal>NULL</literal> parameter string is quoted. For example, with the + default settings, a <literal>NULL</literal> is written as an unquoted empty + string, while an empty string data value is written with double quotes + (<literal>""</literal>). Reading values follows similar rules. You can + use <literal>FORCE_NOT_NULL</literal> to prevent <literal>NULL</literal> input + comparisons for specific columns. You can also use + <literal>FORCE_NULL</literal> to convert quoted null string data values to + <literal>NULL</literal>. + </para> + + <para> + Because backslash is not a special character in the <literal>CSV</literal> + format, <literal>\.</literal>, the end-of-data marker, could also appear + as a data value. To avoid any misinterpretation, a <literal>\.</literal> + data value appearing as a lone entry on a line is automatically + quoted on output, and on input, if quoted, is not interpreted as the + end-of-data marker. If you are loading a file created by another + application that has a single unquoted column and might have a + value of <literal>\.</literal>, you might need to quote that value in the + input file. + </para> + + <note> + <para> + In <literal>CSV</literal> format, all characters are significant. A quoted value + surrounded by white space, or any characters other than + <literal>DELIMITER</literal>, will include those characters. This can cause + errors if you import data from a system that pads <literal>CSV</literal> + lines with white space out to some fixed width. If such a situation + arises you might need to preprocess the <literal>CSV</literal> file to remove + the trailing white space, before importing the data into + <productname>PostgreSQL</productname>. + </para> + </note> + + <note> + <para> + CSV format will both recognize and produce CSV files with quoted + values containing embedded carriage returns and line feeds. Thus + the files are not strictly one line per table row like text-format + files. + </para> + </note> + + <note> + <para> + Many programs produce strange and occasionally perverse CSV files, + so the file format is more a convention than a standard. Thus you + might encounter some files that cannot be imported using this + mechanism, and <command>COPY</command> might produce files that other + programs cannot process. + </para> + </note> + + </refsect2> + + <refsect2> + <title>Binary Format</title> + + <para> + The <literal>binary</literal> format option causes all data to be + stored/read as binary format rather than as text. It is + somewhat faster than the text and <literal>CSV</literal> formats, + but a binary-format file is less portable across machine architectures and + <productname>PostgreSQL</productname> versions. + Also, the binary format is very data type specific; for example + it will not work to output binary data from a <type>smallint</type> column + and read it into an <type>integer</type> column, even though that would work + fine in text format. + </para> + + <para> + The <literal>binary</literal> file format consists + of a file header, zero or more tuples containing the row data, and + a file trailer. Headers and data are in network byte order. + </para> + + <note> + <para> + <productname>PostgreSQL</productname> releases before 7.4 used a + different binary file format. + </para> + </note> + + <refsect3> + <title>File Header</title> + + <para> + The file header consists of 15 bytes of fixed fields, followed + by a variable-length header extension area. The fixed fields are: + + <variablelist> + <varlistentry> + <term>Signature</term> + <listitem> + <para> +11-byte sequence <literal>PGCOPY\n\377\r\n\0</literal> — note that the zero byte +is a required part of the signature. (The signature is designed to allow +easy identification of files that have been munged by a non-8-bit-clean +transfer. This signature will be changed by end-of-line-translation +filters, dropped zero bytes, dropped high bits, or parity changes.) + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term>Flags field</term> + <listitem> + <para> +32-bit integer bit mask to denote important aspects of the file format. Bits +are numbered from 0 (<acronym>LSB</acronym>) to 31 (<acronym>MSB</acronym>). Note that +this field is stored in network byte order (most significant byte first), +as are all the integer fields used in the file format. Bits +16–31 are reserved to denote critical file format issues; a reader +should abort if it finds an unexpected bit set in this range. Bits 0–15 +are reserved to signal backwards-compatible format issues; a reader +should simply ignore any unexpected bits set in this range. Currently +only one flag bit is defined, and the rest must be zero: + <variablelist> + <varlistentry> + <term>Bit 16</term> + <listitem> + <para> + If 1, OIDs are included in the data; if 0, not. Oid system columns + are not supported in <productname>PostgreSQL</productname> + anymore, but the format still contains the indicator. + </para> + </listitem> + </varlistentry> + </variablelist></para> + </listitem> + </varlistentry> + + <varlistentry> + <term>Header extension area length</term> + <listitem> + <para> +32-bit integer, length in bytes of remainder of header, not including self. +Currently, this is zero, and the first tuple follows +immediately. Future changes to the format might allow additional data +to be present in the header. A reader should silently skip over any header +extension data it does not know what to do with. + </para> + </listitem> + </varlistentry> + </variablelist> + </para> + + <para> +The header extension area is envisioned to contain a sequence of +self-identifying chunks. The flags field is not intended to tell readers +what is in the extension area. Specific design of header extension contents +is left for a later release. + </para> + + <para> + This design allows for both backwards-compatible header additions (add + header extension chunks, or set low-order flag bits) and + non-backwards-compatible changes (set high-order flag bits to signal such + changes, and add supporting data to the extension area if needed). + </para> + </refsect3> + + <refsect3> + <title>Tuples</title> + <para> +Each tuple begins with a 16-bit integer count of the number of fields in the +tuple. (Presently, all tuples in a table will have the same count, but that +might not always be true.) Then, repeated for each field in the tuple, there +is a 32-bit length word followed by that many bytes of field data. (The +length word does not include itself, and can be zero.) As a special case, +-1 indicates a NULL field value. No value bytes follow in the NULL case. + </para> + + <para> +There is no alignment padding or any other extra data between fields. + </para> + + <para> +Presently, all data values in a binary-format file are +assumed to be in binary format (format code one). It is anticipated that a +future extension might add a header field that allows per-column format codes +to be specified. + </para> + + <para> +To determine the appropriate binary format for the actual tuple data you +should consult the <productname>PostgreSQL</productname> source, in +particular the <function>*send</function> and <function>*recv</function> functions for +each column's data type (typically these functions are found in the +<filename>src/backend/utils/adt/</filename> directory of the source +distribution). + </para> + + <para> +If OIDs are included in the file, the OID field immediately follows the +field-count word. It is a normal field except that it's not included in the +field-count. Note that oid system columns are not supported in current +versions of <productname>PostgreSQL</productname>. + </para> + </refsect3> + + <refsect3> + <title>File Trailer</title> + + <para> + The file trailer consists of a 16-bit integer word containing -1. This + is easily distinguished from a tuple's field-count word. + </para> + + <para> + A reader should report an error if a field-count word is neither -1 + nor the expected number of columns. This provides an extra + check against somehow getting out of sync with the data. + </para> + </refsect3> + </refsect2> + </refsect1> + + <refsect1> + <title>Examples</title> + + <para> + The following example copies a table to the client + using the vertical bar (<literal>|</literal>) as the field delimiter: +<programlisting> +COPY country TO STDOUT (DELIMITER '|'); +</programlisting> + </para> + + <para> + To copy data from a file into the <literal>country</literal> table: +<programlisting> +COPY country FROM '/usr1/proj/bray/sql/country_data'; +</programlisting> + </para> + + <para> + To copy into a file just the countries whose names start with 'A': +<programlisting> +COPY (SELECT * FROM country WHERE country_name LIKE 'A%') TO '/usr1/proj/bray/sql/a_list_countries.copy'; +</programlisting> + </para> + + <para> + To copy into a compressed file, you can pipe the output through an external + compression program: +<programlisting> +COPY country TO PROGRAM 'gzip > /usr1/proj/bray/sql/country_data.gz'; +</programlisting> + </para> + + <para> + Here is a sample of data suitable for copying into a table from + <literal>STDIN</literal>: +<programlisting> +AF AFGHANISTAN +AL ALBANIA +DZ ALGERIA +ZM ZAMBIA +ZW ZIMBABWE +</programlisting> + Note that the white space on each line is actually a tab character. + </para> + + <para> + The following is the same data, output in binary format. + The data is shown after filtering through the + Unix utility <command>od -c</command>. The table has three columns; + the first has type <type>char(2)</type>, the second has type <type>text</type>, + and the third has type <type>integer</type>. All the rows have a null value + in the third column. +<programlisting> +0000000 P G C O P Y \n 377 \r \n \0 \0 \0 \0 \0 \0 +0000020 \0 \0 \0 \0 003 \0 \0 \0 002 A F \0 \0 \0 013 A +0000040 F G H A N I S T A N 377 377 377 377 \0 003 +0000060 \0 \0 \0 002 A L \0 \0 \0 007 A L B A N I +0000100 A 377 377 377 377 \0 003 \0 \0 \0 002 D Z \0 \0 \0 +0000120 007 A L G E R I A 377 377 377 377 \0 003 \0 \0 +0000140 \0 002 Z M \0 \0 \0 006 Z A M B I A 377 377 +0000160 377 377 \0 003 \0 \0 \0 002 Z W \0 \0 \0 \b Z I +0000200 M B A B W E 377 377 377 377 377 377 +</programlisting></para> + </refsect1> + + <refsect1> + <title>Compatibility</title> + + <para> + There is no <command>COPY</command> statement in the SQL standard. + </para> + + <para> + The following syntax was used before <productname>PostgreSQL</productname> + version 9.0 and is still supported: + +<synopsis> +COPY <replaceable class="parameter">table_name</replaceable> [ ( <replaceable class="parameter">column_name</replaceable> [, ...] ) ] + FROM { '<replaceable class="parameter">filename</replaceable>' | STDIN } + [ [ WITH ] + [ BINARY ] + [ DELIMITER [ AS ] '<replaceable class="parameter">delimiter_character</replaceable>' ] + [ NULL [ AS ] '<replaceable class="parameter">null_string</replaceable>' ] + [ CSV [ HEADER ] + [ QUOTE [ AS ] '<replaceable class="parameter">quote_character</replaceable>' ] + [ ESCAPE [ AS ] '<replaceable class="parameter">escape_character</replaceable>' ] + [ FORCE NOT NULL <replaceable class="parameter">column_name</replaceable> [, ...] ] ] ] + +COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable class="parameter">column_name</replaceable> [, ...] ) ] | ( <replaceable class="parameter">query</replaceable> ) } + TO { '<replaceable class="parameter">filename</replaceable>' | STDOUT } + [ [ WITH ] + [ BINARY ] + [ DELIMITER [ AS ] '<replaceable class="parameter">delimiter_character</replaceable>' ] + [ NULL [ AS ] '<replaceable class="parameter">null_string</replaceable>' ] + [ CSV [ HEADER ] + [ QUOTE [ AS ] '<replaceable class="parameter">quote_character</replaceable>' ] + [ ESCAPE [ AS ] '<replaceable class="parameter">escape_character</replaceable>' ] + [ FORCE QUOTE { <replaceable class="parameter">column_name</replaceable> [, ...] | * } ] ] ] +</synopsis> + + Note that in this syntax, <literal>BINARY</literal> and <literal>CSV</literal> are + treated as independent keywords, not as arguments of a <literal>FORMAT</literal> + option. + </para> + + <para> + The following syntax was used before <productname>PostgreSQL</productname> + version 7.3 and is still supported: + +<synopsis> +COPY [ BINARY ] <replaceable class="parameter">table_name</replaceable> + FROM { '<replaceable class="parameter">filename</replaceable>' | STDIN } + [ [USING] DELIMITERS '<replaceable class="parameter">delimiter_character</replaceable>' ] + [ WITH NULL AS '<replaceable class="parameter">null_string</replaceable>' ] + +COPY [ BINARY ] <replaceable class="parameter">table_name</replaceable> + TO { '<replaceable class="parameter">filename</replaceable>' | STDOUT } + [ [USING] DELIMITERS '<replaceable class="parameter">delimiter_character</replaceable>' ] + [ WITH NULL AS '<replaceable class="parameter">null_string</replaceable>' ] +</synopsis></para> + </refsect1> + + <refsect1> + <title>See Also</title> + + <simplelist type="inline"> + <member><xref linkend="copy-progress-reporting"/></member> + </simplelist> + </refsect1> +</refentry> |