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https://github.com/dimitri/pgloader.git
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Implement header parsing for fixed file formats.
Fixed file formats might contain an header line with column names and a hint of the size of each column. While it might be a long shot that we can acutally use that as a proper fixed-format specification, this patch implements a guess mode that also outputs the parsed header. In case when the parsing is wrong in some level of details, it might actually be a good start to copy/paste from the command output and go from there. Fixes #958.
This commit is contained in:
Dimitri Fontaine
parent
27b1a83b9f
commit
b1d55e07d6
@ -130,8 +130,12 @@
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;; (:file "csv-database")
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(:file "csv")))
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(:file "fixed"
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:depends-on ("common" "csv"))
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(:module "fixed"
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:depends-on ("common")
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:serial t
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:components
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((:file "fixed-guess")
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(:file "fixed")))
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(:file "copy"
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:depends-on ("common" "csv"))
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@ -7,6 +7,9 @@
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(in-package #:pgloader.parser)
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(defrule option-fixed-header (and kw-fixed kw-header)
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(:constant (cons :header t)))
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(defrule hex-number (and "0x" (+ (hexdigit-char-p character)))
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(:lambda (hex)
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(bind (((_ digits) hex))
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@ -55,7 +58,8 @@
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option-drop-indexes
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option-disable-triggers
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option-identifiers-case
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option-skip-header))
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option-skip-header
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option-fixed-header))
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(defrule fixed-options (and kw-with
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(and fixed-option (* (and comma fixed-option))))
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@ -94,7 +98,7 @@
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(alexandria:alist-plist clauses-list)))
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(defrule load-fixed-cols-file-command (and fixed-source (? file-encoding)
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fixed-source-field-list
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(? fixed-source-field-list)
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target
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(? csv-target-table)
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(? csv-target-column-list)
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@ -144,7 +148,8 @@
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:encoding ,encoding
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:fields ',fields
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:columns ',columns
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:skip-lines ,(or (getf options :skip-line) 0))))
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:skip-lines ,(or (getf options :skip-lines) 0)
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:header ,(getf options :header))))
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(copy-database source
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,@ (when worker-count
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74
src/sources/fixed/fixed-guess.lisp
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74
src/sources/fixed/fixed-guess.lisp
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@ -0,0 +1,74 @@
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;;;
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;;; Given a list of columns in PostgreSQL, try to guess the fixed format
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;;; specification from a sample of the file.
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;;;
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(in-package :pgloader.source.fixed)
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(defgeneric get-first-lines (filename-or-stream &optional n)
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(:documentation "Get the first line of given FILENAME-OR-STREAM.")
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(:method ((stream stream) &optional (n 1))
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(let ((pos (file-position stream)))
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(file-position stream 0)
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(prog1
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(loop :repeat n
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:for line := (read-line stream nil nil)
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:while line
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:collect line)
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(file-position stream pos))))
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(:method ((filename string) &optional (n 1))
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(with-open-file (stream filename
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:direction :input
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:external-format :utf-8
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:if-does-not-exist nil)
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(loop :repeat n
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:for line := (read-line stream nil nil)
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:while line
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:collect line))))
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(defun guess-fixed-specs-from-header (header)
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"Try to guess fixed specs from whitespace in the first line of the file."
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(let* ((size (length header))
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current-field-name (current-field-start 0)
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specs)
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(loop :for pos :from 0
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:for previous-char := #\Space :then current-char
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:for current-char :across header
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:do (cond ((or (= (+ 1 pos) size) ; last char
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(and (< 0 pos) ; new field
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(char= #\Space previous-char)
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(char/= #\Space current-char)))
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(when (= (+ 1 pos) size)
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(push current-char current-field-name))
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(push (list (map 'string #'identity
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(reverse current-field-name))
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:start current-field-start
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:length (- pos current-field-start)
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:null-as :blanks
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:trim-right t)
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specs)
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(setf current-field-name (list current-char))
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(setf current-field-start pos))
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((char/= #\Space current-char)
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(push current-char current-field-name))))
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(reverse specs)))
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(defun guess-fixed-specs (filename-or-stream &optional (sample-size 1000))
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"Use the first line as an header to guess the specification of the fixed
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file from, and then match that against a sample of data from the file to
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see if that matches what data we have there."
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(let* ((sample (get-first-lines filename-or-stream sample-size))
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(header (first sample))
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(data (rest sample))
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(fields (guess-fixed-specs-from-header header))
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(specs (mapcar #'cdr fields)))
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(loop :for line :in data
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:collect (handler-case
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(parse-row specs line)
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(condition (e)
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(log-message :error
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"Fixed: failed to use header as ~
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specification for columns: ~a" e)
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(return-from guess-fixed-specs nil))))
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fields))
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@ -10,12 +10,7 @@
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"Assign the type slot to sqlite."
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(setf (slot-value fixed 'type) "fixed"))
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(defclass copy-fixed (md-copy)
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((encoding :accessor encoding ; file encoding
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:initarg :encoding) ;
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(skip-lines :accessor skip-lines ; CSV headers
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:initarg :skip-lines ;
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:initform 0))
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(defclass copy-fixed (md-copy) ()
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(:documentation "pgloader Fixed Columns Data Source"))
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(defmethod clone-copy-for ((fixed copy-fixed) path-spec)
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@ -30,6 +25,29 @@
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;; return the new instance!
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fixed-clone))
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(defmethod parse-header ((fixed copy-fixed))
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"Parse the header line given a FIXED setup."
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(with-connection (cnx (source fixed)
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:direction :input
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:external-format (encoding fixed)
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:if-does-not-exist nil)
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(let ((input (md-strm cnx)))
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(loop :repeat (skip-lines fixed) :do (read-line input nil nil))
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(let* ((field-spec-list (guess-fixed-specs input))
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(specifications
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(loop :for specs :in field-spec-list
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:collect (destructuring-bind (name &key start length
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&allow-other-keys)
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specs
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(format nil
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"~a from ~d for ~d ~a"
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name start length
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"[null if blanks, trim right whitespace]")))))
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(setf (fields fixed) field-spec-list)
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(log-message :log
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"Parsed ~d columns specs from header:~%(~%~{ ~a~^,~%~}~%)"
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(length (fields fixed)) specifications)))))
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(declaim (inline parse-row))
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(defun parse-row (fixed-cols-specs line)
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7
test/fixed-guess.dat
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7
test/fixed-guess.dat
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@ -0,0 +1,7 @@
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QECDPO QECSEM QELSEM QERSEM QENCOM QESCRE QEACRE QEMCRE QEJCRE QEHCRE QECUCR QESMAJ QEAMAJ QEMMAJ QEJMAJ QEHMAJ QECUMJ QETOPD
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ACT INV Inventaire par niveau Par niveau 0 20 7 10 29 180457 HLJFD 20 7 10 29 180457 HLJFD 0
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ACT IPI Inventaire pickings / colonnes Picking / Colo. 0 20 8 4 28 164330 HLJFD 20 8 4 28 164330 HLJFD 0
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ACT STB SEQUENCE STANDARD BACKUP STANDARD 0 20 12 11 13 154308 HLJFL 20 12 11 13 154308 HLJFL 0
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ACT STC SEQUENCE backup 250913 STANDARD 0 20 13 9 25 161133 HLJFL 20 13 9 25 161133 HLJFL 0
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ACT STD SEQUENCE STANDARD STANDARD 0 20 12 11 13 154813 HLJFL 20 12 11 13 154813 HLJFL 0
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ACT TTT test test 0 20 12 11 13 102211 HLJFL 20 12 11 13 102211 HLJFL 0
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36
test/fixed-guess.load
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36
test/fixed-guess.load
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@ -0,0 +1,36 @@
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LOAD FIXED
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FROM fixed-guess.dat
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INTO postgresql:///pgloader
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TARGET TABLE fixed.guess
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WITH fixed header
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SET work_mem to '14MB',
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standard_conforming_strings to 'on'
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before load do
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$$ create schema if not exists fixed; $$,
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$$ drop table if exists fixed.guess; $$,
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$$
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create table fixed.guess
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(
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QECDPO character varying(3),
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QECSEM character varying(3),
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QELSEM character varying(30),
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QERSEM character varying(15),
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QENCOM integer,
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QESCRE smallint,
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QEACRE smallint,
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QEMCRE smallint,
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QEJCRE smallint,
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QEHCRE integer,
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QECUCR character varying(10),
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QESMAJ smallint,
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QEAMAJ smallint,
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QEMMAJ smallint,
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QEJMAJ smallint,
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QEHMAJ integer,
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QECUMJ character varying(10),
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QETOPD character varying(1)
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);
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$$ ;
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