Class: MiqSqlite3DB::MiqSqlite3

Inherits:
Object
  • Object
show all
Defined in:
lib/db/MiqSqlite/MiqSqlite3.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(fileName = nil, fs = nil) ⇒ MiqSqlite3

Returns a new instance of MiqSqlite3.



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# File 'lib/db/MiqSqlite/MiqSqlite3.rb', line 228

def initialize(fileName = nil, fs = nil)
  @fs = fs unless fs.nil?
  open(fileName) unless fileName.nil?

  if  @pageSize < 512 || @pageSize > SQLITE_MAX_PAGE_SIZE || ((@pageSize - 1) & @pageSize) != 0
    #        @pageSize = 0
    #        sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize);
    @maxEmbedFrac = 64   # 25.0%
    @minEmbedFrac = 32   # 12.5%
    @minLeafFrac  = 32   # 12.5%
    @nReserve     = 0
  else
    @nReserve     = @header.unused_space
    @maxEmbedFrac = @header.max_payload_node_fraction
    @minEmbedFrac = @header.min_payload_node_fraction
    @minLeafFrac  = @header.min_payload_leaf_fraction
    @pageSizeFixed = true
  end

  @usableSize = @pageSize - @nReserve
  #      assert( (pBt->pageSize & 7)==0 );  /* 8-byte alignment of pageSize */

  #########################################################################
  # /* maxLocal is the maximum amount of payload to store locally for
  # ** a cell.  Make sure it is small enough so that at least minFanout
  # ** cells can will fit on one page.  We assume a 10-byte page header.
  # ** Besides the payload, the cell must store:
  # **     2-byte pointer to the cell
  # **     4-byte child pointer
  # **     9-byte nKey value
  # **     4-byte nData value
  # **     4-byte overflow page pointer
  # ** So a cell consists of a 2-byte poiner, a header which is as much as
  # ** 17 bytes long, 0 to N bytes of payload, and an optional 4 byte overflow
  # ** page pointer.
  #########################################################################
  @maxLocal = (@usableSize - 12) * @maxEmbedFrac / 255 - 23
  @minLocal = (@usableSize - 12) * @minEmbedFrac / 255 - 23
  @maxLeaf  = @usableSize - 35
  @minLeaf  = (@usableSize - 12) * @minLeafFrac / 255 - 23
end

Instance Attribute Details

#maxLeaf ⇒ Object (readonly)

Returns the value of attribute maxLeaf.



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# File 'lib/db/MiqSqlite/MiqSqlite3.rb', line 226

def maxLeaf
  @maxLeaf
end

#maxLocal ⇒ Object (readonly)

Returns the value of attribute maxLocal.



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# File 'lib/db/MiqSqlite/MiqSqlite3.rb', line 226

def maxLocal
  @maxLocal
end

#minLeaf ⇒ Object (readonly)

Returns the value of attribute minLeaf.



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# File 'lib/db/MiqSqlite/MiqSqlite3.rb', line 226

def minLeaf
  @minLeaf
end

#minLocal ⇒ Object (readonly)

Returns the value of attribute minLocal.



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# File 'lib/db/MiqSqlite/MiqSqlite3.rb', line 226

def minLocal
  @minLocal
end

#npages ⇒ Object (readonly)

Returns the value of attribute npages.



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# File 'lib/db/MiqSqlite/MiqSqlite3.rb', line 226

def npages
  @npages
end

#pageSize ⇒ Object (readonly)

Returns the value of attribute pageSize.



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# File 'lib/db/MiqSqlite/MiqSqlite3.rb', line 226

def pageSize
  @pageSize
end

#usableSize ⇒ Object (readonly)

Returns the value of attribute usableSize.



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# File 'lib/db/MiqSqlite/MiqSqlite3.rb', line 226

def usableSize
  @usableSize
end

Instance Method Details

#close ⇒ Object

Close the database



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# File 'lib/db/MiqSqlite/MiqSqlite3.rb', line 284

def close
  @db.close   if @db
  @file.close if @file
  @db = @header = @file = @filename = nil
end

#each_page ⇒ Object 



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# File 'lib/db/MiqSqlite/MiqSqlite3.rb', line 290

def each_page
  for pagenum in 1..npages
    yield MiqSqlite3Page.getPage(self, pagenum)
  end
end

#getTable(name) ⇒ Object 



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# File 'lib/db/MiqSqlite/MiqSqlite3.rb', line 310

def getTable(name)
  MiqSqlite3Table.getTable(self, name)
end

#open(filename) ⇒ Object

Open the database



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# File 'lib/db/MiqSqlite/MiqSqlite3.rb', line 271

def open(filename)
  # Get header & check.
  @filename = filename
  @file     = fileOpen(@filename)
  @header   = OpenStruct.new(DBHEADER.decode(@file.read(SIZEOF_DBHEADER)))
  @pageSize = @header.page_size
  @npages   = fileSize / @pageSize

  raise "#{@filename} is not a SQLite3 Database."                                 if @header.magic != "SQLite format 3\000"
  raise "#{@filename} is corrupt -- has incomplete pages (pagesize=#{@pageSize})" if (@pageSize * @npages) != fileSize
end

#readPage(pagenum) ⇒ Object 



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# File 'lib/db/MiqSqlite/MiqSqlite3.rb', line 296

def readPage(pagenum)
  where = (pagenum - 1) * @pageSize
  @file.seek(where)
  @file.read(@pageSize)
end

#size ⇒ Object 



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# File 'lib/db/MiqSqlite/MiqSqlite3.rb', line 302

def size
  fileSize
end

#table_names ⇒ Object 



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# File 'lib/db/MiqSqlite/MiqSqlite3.rb', line 306

def table_names
  MiqSqlite3Table.table_names(self)
end