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|
const std = @import("std");
const varint = @import("varint.zig");
const record = @import("record.zig");
const btree = @import("btree.zig");
const index = @import("index.zig");
const schema = @import("schema.zig");
/// Read a specific record by rowid from table
fn readRecordByRowid(allocator: std.mem.Allocator, file: *std.fs.File, page_size: u16, table_rootpage: u32, target_rowid: u64, column_indices: []const usize, stdout: anytype) !void {
try searchTableForRowid(allocator, file, page_size, table_rootpage, target_rowid, column_indices, stdout);
}
/// Search for a specific rowid in table B-tree
fn searchTableForRowid(allocator: std.mem.Allocator, file: *std.fs.File, page_size: u16, page_num: u32, target_rowid: u64, column_indices: []const usize, stdout: anytype) !void {
var current_page = page_num;
var depth: u32 = 0;
const max_depth = 50;
while (current_page != 0 and depth < max_depth) {
depth += 1;
const page_offset = (current_page - 1) * @as(u64, page_size);
var page_data = try allocator.alloc(u8, page_size);
defer allocator.free(page_data);
_ = try file.seekTo(page_offset);
_ = try file.read(page_data);
const page_type = page_data[0];
if (page_type == 0x0d) {
// Leaf table page
const num_cells = std.mem.readInt(u16, page_data[3..5], .big);
for (0..num_cells) |i| {
const offset = 8 + i * 2;
if (offset + 2 > page_data.len) continue;
const cell_ptr = std.mem.readInt(u16, page_data[offset..][0..2], .big);
if (cell_ptr >= page_data.len) continue;
const cell_data = page_data[cell_ptr..];
var parsed = varint.parse(cell_data);
var pos = parsed.len;
if (pos >= cell_data.len) continue;
parsed = varint.parse(cell_data[pos..]);
const rowid = parsed.value;
pos += parsed.len;
if (pos >= cell_data.len) continue;
if (rowid == target_rowid) {
const record_data = cell_data[pos..];
parsed = varint.parse(record_data);
const header_size = parsed.value;
if (header_size > record_data.len) continue;
var header_pos = parsed.len;
var serial_types = std.ArrayList(u64){};
defer serial_types.deinit(allocator);
while (header_pos < header_size) {
parsed = varint.parse(record_data[header_pos..]);
serial_types.append(allocator, parsed.value) catch break;
header_pos += parsed.len;
}
for (column_indices, 0..) |column_idx, col_num| {
if (col_num > 0) try stdout.print("|", .{});
if (column_idx >= serial_types.items.len) continue;
var body_pos: usize = header_size;
for (0..column_idx) |col| {
if (col >= serial_types.items.len) break;
const st = serial_types.items[col];
if (st == 0 or st == 8 or st == 9) {
// NULL, 0, or 1 - no data
} else if (st >= 13 and (st % 2) == 1) {
body_pos += (st - 13) / 2;
} else if (st >= 12 and (st % 2) == 0) {
body_pos += (st - 12) / 2;
} else if (st >= 1 and st <= 6) {
const int_result = record.readInt(record_data[body_pos..], st);
body_pos += int_result.len;
} else if (st == 7) {
body_pos += 8;
}
}
const st = serial_types.items[column_idx];
if (st == 0) {
try stdout.print("{}", .{rowid});
} else if (st == 8) {
try stdout.print("0", .{});
} else if (st == 9) {
try stdout.print("1", .{});
} else if (st >= 1 and st <= 6) {
const int_result = record.readInt(record_data[body_pos..], st);
try stdout.print("{}", .{int_result.value});
} else if (st == 7) {
const float_result = record.readFloat(record_data[body_pos..]);
try stdout.print("{d}", .{float_result.value});
} else if (st >= 13 and (st % 2) == 1) {
const str_result = record.readString(record_data[body_pos..], st);
try stdout.print("{s}", .{str_result.value});
}
}
try stdout.print("\n", .{});
return;
}
}
return;
} else if (page_type == 0x05) {
// Interior table page
const num_cells = std.mem.readInt(u16, page_data[3..5], .big);
var next_page: u32 = 0;
for (0..num_cells) |i| {
const offset = 12 + i * 2;
if (offset + 2 > page_data.len) continue;
const cell_ptr = std.mem.readInt(u16, page_data[offset..][0..2], .big);
if (cell_ptr + 8 > page_data.len) continue;
const cell_data = page_data[cell_ptr..];
const left_child_page = std.mem.readInt(u32, cell_data[0..4], .big);
const parsed = varint.parse(cell_data[4..]);
const key = parsed.value;
if (target_rowid <= key) {
next_page = left_child_page;
break;
}
}
if (next_page == 0) {
next_page = std.mem.readInt(u32, page_data[8..12], .big);
}
current_page = next_page;
} else {
return;
}
}
}
/// Read table rows - single column
pub fn readTableRows(allocator: std.mem.Allocator, file: *std.fs.File, page_size: u16, rootpage: u32, column_idx: usize, stdout: anytype) !void {
if (rootpage == 0) return;
const page_offset = (rootpage - 1) * @as(u64, page_size);
var page_data = try allocator.alloc(u8, page_size);
defer allocator.free(page_data);
_ = try file.seekTo(page_offset);
_ = try file.read(page_data);
const page_type = page_data[0];
if (page_type != 0x0d) return;
const num_cells = std.mem.readInt(u16, page_data[3..5], .big);
var cell_pointers = try allocator.alloc(u16, num_cells);
defer allocator.free(cell_pointers);
for (0..num_cells) |i| {
const offset = 8 + i * 2;
const cell_ptr_bytes = page_data[offset .. offset + 2];
cell_pointers[i] = std.mem.readInt(u16, cell_ptr_bytes[0..2], .big);
}
for (0..num_cells) |i| {
const cell_data = page_data[cell_pointers[i]..];
var parsed = varint.parse(cell_data);
var pos = parsed.len;
parsed = varint.parse(cell_data[pos..]);
pos += parsed.len;
const record_data = cell_data[pos..];
parsed = varint.parse(record_data);
const header_size = parsed.value;
var header_pos = parsed.len;
var serial_types = std.ArrayList(u64){};
defer serial_types.deinit(allocator);
while (header_pos < header_size) {
parsed = varint.parse(record_data[header_pos..]);
try serial_types.append(allocator, parsed.value);
header_pos += parsed.len;
}
if (column_idx >= serial_types.items.len) continue;
var body_pos: usize = header_size;
for (0..column_idx) |col| {
if (col >= serial_types.items.len) break;
const st = serial_types.items[col];
if (st >= 13 and (st % 2) == 1) {
body_pos += (st - 13) / 2;
} else if (st >= 1 and st <= 6) {
const int_result = record.readInt(record_data[body_pos..], st);
body_pos += int_result.len;
}
}
const st = serial_types.items[column_idx];
if (st >= 13 and (st % 2) == 1) {
const str_result = record.readString(record_data[body_pos..], st);
try stdout.print("{s}\n", .{str_result.value});
} else if (st >= 1 and st <= 6) {
const int_result = record.readInt(record_data[body_pos..], st);
try stdout.print("{}\n", .{int_result.value});
}
}
}
/// Read table rows - multiple columns
pub fn readTableRowsMultiColumn(allocator: std.mem.Allocator, file: *std.fs.File, page_size: u16, rootpage: u32, column_indices: []const usize, stdout: anytype) !void {
if (rootpage == 0) return;
const page_offset = (rootpage - 1) * @as(u64, page_size);
var page_data = try allocator.alloc(u8, page_size);
defer allocator.free(page_data);
_ = try file.seekTo(page_offset);
_ = try file.read(page_data);
const page_type = page_data[0];
if (page_type != 0x0d) return;
const num_cells = std.mem.readInt(u16, page_data[3..5], .big);
var cell_pointers = try allocator.alloc(u16, num_cells);
defer allocator.free(cell_pointers);
for (0..num_cells) |i| {
const offset = 8 + i * 2;
const cell_ptr_bytes = page_data[offset .. offset + 2];
cell_pointers[i] = std.mem.readInt(u16, cell_ptr_bytes[0..2], .big);
}
for (0..num_cells) |i| {
const cell_data = page_data[cell_pointers[i]..];
var parsed = varint.parse(cell_data);
var pos = parsed.len;
parsed = varint.parse(cell_data[pos..]);
pos += parsed.len;
const record_data = cell_data[pos..];
parsed = varint.parse(record_data);
const header_size = parsed.value;
var header_pos = parsed.len;
var serial_types = std.ArrayList(u64){};
defer serial_types.deinit(allocator);
while (header_pos < header_size) {
parsed = varint.parse(record_data[header_pos..]);
try serial_types.append(allocator, parsed.value);
header_pos += parsed.len;
}
for (column_indices, 0..) |column_idx, col_num| {
var body_pos: usize = header_size;
for (0..column_idx) |col| {
if (col >= serial_types.items.len) break;
const st = serial_types.items[col];
if (st >= 13 and (st % 2) == 1) {
body_pos += (st - 13) / 2;
} else if (st >= 1 and st <= 6) {
const int_result = record.readInt(record_data[body_pos..], st);
body_pos += int_result.len;
}
}
if (col_num > 0) {
try stdout.print("|", .{});
}
if (column_idx < serial_types.items.len) {
const st = serial_types.items[column_idx];
if (st >= 13 and (st % 2) == 1) {
const str_result = record.readString(record_data[body_pos..], st);
try stdout.print("{s}", .{str_result.value});
} else if (st >= 1 and st <= 6) {
const int_result = record.readInt(record_data[body_pos..], st);
try stdout.print("{}", .{int_result.value});
}
}
}
try stdout.print("\n", .{});
}
}
/// Read table rows with WHERE clause - uses optimized B-tree traversal
pub fn readTableRowsMultiColumnWhere(allocator: std.mem.Allocator, file: *std.fs.File, page_size: u16, rootpage: u32, column_indices: []const usize, where_column_idx: ?usize, where_value: ?[]const u8, stdout: anytype) !void {
try btree.traverseBTree(allocator, file, page_size, rootpage, column_indices, where_column_idx, where_value, stdout);
}
/// Read table rows using index scan
pub fn readTableRowsWithIndex(allocator: std.mem.Allocator, file: *std.fs.File, page_size: u16, table_name: []const u8, table_rootpage: u32, column_indices: []const usize, where_column: []const u8, where_value: []const u8, stdout: anytype) !void {
_ = allocator;
_ = file;
_ = page_size;
_ = table_name;
_ = table_rootpage;
_ = column_indices;
_ = where_column;
_ = where_value;
_ = stdout;
// Index scan disabled - use optimized table scan
return error.NoIndexFound;
}
|
