Queries

Search by Prefix

Find all entries with a given prefix:

const results = try db.search(.{ .prefix = "user:" });
defer results.deinit(allocator);

for (results.items) |entry| {
    std.debug.print("{s} = {s}\n", .{ entry.key, entry.value });
}

Filter by Predicate

Filter entries with a custom function:

const results = try db.filter(null, struct {
    fn is_admin(_: void, e: zkv.Entry) bool {
        return std.mem.eql(u8, e.value, "admin");
    }
}.is_admin, .{});
defer results.deinit(allocator);

TIP

Use filter() for complex queries that cannot be expressed with prefix matching alone.

Find First Match

Return the first entry matching a predicate:

const found = db.find(null, struct {
    fn is_user(_: void, e: zkv.Entry) bool {
        return std.mem.startsWith(u8, e.key, "user:");
    }
}.is_user);

Find and Replace

Replace values for matching entries:

const replaced = try db.findAndReplace(null, struct {
    fn is_viewer(_: void, e: zkv.Entry) bool {
        return std.mem.eql(u8, e.value, "viewer");
    }
}.is_viewer, "moderator");

Sorted Entries

Retrieve entries sorted by a comparator:

const sorted = try db.sortedEntries(null, struct {
    fn cmp(_: void, a: zkv.Entry, b: zkv.Entry) std.math.Order {
        return std.mem.order(u8, a.key, b.key);
    }
}.cmp, .{});
defer sorted.deinit(allocator);

Iterator

Iterate over a key range:

var it = db.iterator("user:1", "user:3") orelse return;
while (it.next()) |entry| {
    std.debug.print("{s} => {s}\n", .{ entry.key, entry.value });
}

Collection Prefix Iteration

const users = db.collection("users");
var iter = users.prefix("1:");
while (iter.next()) |entry| {
    std.debug.print("{s} = {s}\n", .{ entry.key, entry.value });
}

Collection Range Query

const items = db.collection("items");
var result = items.range("a", "d");
defer result.deinit(allocator);

NOTE

Range queries are inclusive on both ends. Use prefix() for all entries starting with a given string.